The devs somehow need to get paid or they won't develop FOSS at all.
I'm sorry but that is simply untrue. So many Rust crates, PyPi modules, RubyGems, npm packages, wordpress, TeX, NuGet modules and plugins, and countless Linux and C/C++ libraries as well as the plugins for all of those were made without receiving any sponsorship or donation whatsoever. That is to say nothing about all the applications hosted on Github and Gitlab. Your next paragraph is a bit more correct in that developers somehow need to get money in order to sustain themselves, but usually, it comes from their day jobs and not from the packages they maintain, which is why you don't see much of this kind of problem in FOSS.
You are also correct that some people's living is
only through FOSS development and in that case, funding naturally becomes more important to them.
But who would fund a privacy wallet? Even with bitcoin, nearly all of the dev funding comes from corporations and from the occasional well-meaning tech billionaire. Would these corporations and billionaires want to risk seeming as defying U.S. authorities and regulations though? I think most definitely not.
Continuing my discourse above, the more importance you attach to funding in order to maintain something, the less development you're actually going to do. Because then it becomes a matter of trying to make a wage through community donations, rather than actual development. Ideally, the project funding should be enough to cover the costs of developing and testing the project, but usually the total amount will
not be anything close to a full salary. This is not to say that they don't need funding, but it should be second priority to actually programming the stuff.
That being said, there are crypto funds for the development of such infra, like what Human Rights Foundation has been giving out the past few years.
We can't realistically expect any software development to happen from developers operating without salaries and/or without knowing each other's person, operating in a rogue manner. Feature-packed privacy wallets are vast and can't be developed without any organization. So whoever is organizing things also could face liability against state entities.
Like I wrote earlier, funding is usually not going to be enough to cover salaries, but it will cover the cost of developing the app. All privacy developers and operators from TOR, anyone who makes E2E chat or email programs, and crypto developers will inevitably will be in the crosshairs of a few nation states, but not necessarily because they broke the law. They do need to take basic precautions to not get hurt though, like not talking too much and too loud (as Samourai's social media was well known for being edgy and triggering).
After seeing what happened to Samourai devs, we just have to be glad that Wasabi is still standing and the devs behind it are still willing to provide the software, albeit with limitations. The software existing and being developed is what matters. If anyone wants to use it in whatever ways it should be on them and not in the developers. But if the US gov doesn't see it that way, what can be done?
Most people used Wasabi Wallet for the automatic mixing feature. It is not very useful without that, or if it's sabotaged.
Maybe we could try crowd-fund the development of a privacy coordinator and development team to operate out of Russia or Iran or at least anonymously and not have to worry about them being sent to a U.S. jail. But to my knowledge, no one has taken up to that endeavor and secondly I've seen overall nearly non-existent willingness of users to crowd-fund bitcoin privacy wallets. Let alone the fact that operating our of a non-western state and/or being anonymous doesn't guarantee that developers of such a project will be left alone.
Assembling a team within a US enemy state is a recipe for disaster. That will just incentive them to take down the software and press charges for politics. Not to mention the countries you mentioned have their own police problems. The best thing that can be done is to develop such a thing where you will at least have a chance of a fair trial and free (within reasonable limits) speech. Most of
these tools are developed by teams in those jurisdictions.
As well as the fact that developing a coordinator is simply not enough. Obviously it would have to be decentralized first of all, but we saw with Tornado Cash that even decentralized coordinators/mixers can be held liable for "Money Transmission Service" even if they are not living in the west. It requires a community, similar to the communities of Tor and Bitcoin. The reason why the feds simply can't outright ban those two technologies is that they have a large enough userbase that it can be clearly seen that it is being used for
legal purposes as well. Ditto with secure email, confidential tipping services, secure chat, secure DNS resolvers, VPNs and so on.
Mixing tools are no different. The proof of that is that there is not a single western government that has made Monero illegal yet.
Of course, Uncle Sam don't actually care whether your service is operating within the law or not, and as soon as he sees a vulnerable project like the one whose thread I'm replying in, he becomes prime John Cena and body-slams you until you're either bankrupted, jailed, or otherwise ruined from being on a wanted list.
They can't do that if you have lawyers, that is why increased legal representation for open-source projects is so important. Most projects can't afford a lawyer and the funding should be going to that, not towards the dev's livelihood.