Wouldn't finding a drop-in replacement PSU mainly be a matter of knowing the specs for it? Namely:
Output voltage range
Output current
Max power out rating
And here's the most important bit -- how the controller talks to the PSU to set the voltage output fed to the hash boards and if/how the controller knows what the PSU is doing. Is it simple 0-5v analog coming from a DA converter or analog output port on the SoC? Serial coms like I2C? PWM signal? etc.

No, you pretty much nailed it. The efficiency of any decent large power transformer ranges from at least 97% and for premium ones is over 99%. That leaves only the rate plan as a variable when it comes to incoming voltage & power.

Oh, and of course the 1-time cost of the transformer if you have to pay for it If you are the one supplying the transformer this is certainly a case for spending more to get a premium high-efficiency one vs the cheapest you can get. Considering that all of the power will be going through it, when pulling say 100kva through it every 1% difference is 1kva saved or lost. Using a 30 day month that = 720kWh/month so that cost adds up fast.

Did a quick look at their site and do like most of what they show though their miner prices are way out of line with Bitmain's prices. The *most* part is the picture they have of a heavy power circuit breaker 'box' https://i0.wp.com/delmarva.io/wp-content/uploads/2022/08/IMG-2954-scaled.jpg?resize=1536%2C2048&ssl=1
There is no way in hell that setup should have passed the electrical inspection... That plastic box does not stand a chance of surviving a short across any buses inside of it... Electrical distribution enclosures are designed and rated to contain and re-direct the huge explosive force that results from a major cross-phase fault.

Yes there are still scads of shitcoins that can be mined using GPU's. Of course most are also worthless or damn close to it.
Thing is -- this is the Bitcoin area where the sole topic of discussion is BTC. Not the altcoin mining area where all discussion of alts belongs.

And then there the issue of eBang miners historically being utter crap with zero factory support...

Since a certain cloud mining site ad will be no doubt be deleted by the mods, the key line from that ad is BULLSHIT! >99.9% of cloud 'mining' sites are Ponzi scams and have nothing to do with 'investing'. Stay far far away from ANY of them!. Period.

Yes it is their miner sales channel.
The main company site is https://canaan.io/ where you can also look into their AI products.

A good thread to start with is here. The key takeaway from that thread is to take all 'advice' from so-called 'Experts' you come across on youtube, twitter, et al with a large dose of salt.

Beyond that - spend a few days scanning through the various thread here in the Forum. Most often the titles will give a good hint to what they are about.

Without a doubt the Canaan Avalons are more reliable plus Canaan has stock of them in the US so there is no added Import duty to their price when you order directly from them. https://shop.canaan.io

Ja. one MUST always refer to the battery manufacturer website and factory data sheets for the full picture. Actually that applies to buying any power electronic device. Even reputable manufacturer authorized distributors rarely give all the details (but will provide the links you want). Random resellers of things, well.....

There is a 3rd/4th solution as well: Storing the power in large banks of supercapacitors which have a massively long lifetime but do self-discharge or the latest variant of them, hybrid supercapacitors that combine supercaps & Li-ion batteries into 1 device. In essence the caps handle whatever amount of load be it short high-current or long term output with no change in apparent capacity. btw: That article delves quite nicely into what a capacitor is and how they work

Of course both are very expensive but to a point it is balanced by them essentially being zero maint for 10-20+ years.

One available provider of them is https://powerquality.eaton.com/emea/supercapacitor/default.asp Per that page, No doubt using a lower% of full power rating gives more time. In other words long enough for the overall much cheaper (for hours/days/more of running) diesel genset(s) to kick in. Direct link to their supercap only UPS solution http://pqlit.eaton.com/ll_download_bylitcode.asp?doc_id=30241

To be honest, modular plug PSU's all have 1 major problem: They are pushing the maximum current rating through the contacts and generally have only 18ga wires between the PSU and PCIe plugs.
Ok, that's 2 major problems...

That said, since you are talking about running at reduced power it may not be an issue, just periodically check to see how warm the PSU connectors get. Yes, I've had a few rather spectacularly fry over the years from when I used them to power s3's & s5's...

Other thing to keep in mind is that particular PSU has 2 independent output rails. DO NOT connect power from the 2 different rails to 1 hash board! They will be shorted together and fight each other.

Again, please take the time to at least scan through the thread. All your answers are here...
That said - a standard USB port can supply only 0.7 to 1A so yes a powered hub that can supply at least 2A per port aka a 'charging hub' is REQUIRED to run at a decent speed and a made-for-mining hub is required to overclock as the sticks can easily pull 3 or more amps.

Good lord. HDD cache software is still being sold?
Um, it pretty much became a useless bit of kit in the late 1980's once the various OS's started to mature and began to handle disk access more intelligently...

Blockchain technology and Bitcoin are 2 related but different things....
Yes Bitcoin uses a blockchain *but* it is intended and designed to mainly be for monetary transactions - NOT general records keeping.

That said, there are many many real-world uses of blockchain technology that ARE used for records involving that involve tracking food production & distribution, various electronic device production, municipal lighting, long-haul trucking, etc. Publishing is just another variant of that. The key point here is that the blockchains used are tailored to a specific purpose and none of them have anything to do with BTC.

....
Um, since this thread is about the Gekkoscience Compac-F guess what the answer is....  
Where to buy it is last paragraph in the 1st post.

At least it is in correct the Off Topic area `cause it's just about as far from crypto as ya can get
An amusing break from reality though...

Hopefully you will find a way out of this and will have learned to change your ways. If not.... Just another case of Darwin at work...

Um, any PC PSU over 100w that has at least 1 6-pin PCIe connector...

Oh btw: If you insist on using a connector for supplying Vcore then check out Anderson Powerpole connectors like found at https://www.amazon.com/anderson-power-pole/s?k=anderson+power+pole  They are specifically made for low voltage use (but rated up to 600v) and start at 15A with up to 350A capacity. Rather inexpensive as well The companies page is at https://www.andersonpower.com/us/en/resources/PowerPoleResourcesPage.html

The' Best' all depends on the buyer - not some random person's thoughts... Most hardware guides here are pretty clear on that: 1st pick your criteria and choose from either speed, efficiency or, service life and go from there. There are no miners that are the top in all 3 areas.

Personally I use service life as my #1 and that means any of Canaaan's Avalon miners.