Thanks @all - like I said - I wanted to skip having to waste days learning all the new ropes (software, sensible fees, new wallet formats - for every damned fork)... but looks like that's not possible (grr).
And to the skeptic lurking here, bzzt. nope. everything I said is true. (and yeah, to be fair, for every one of me, there probably are ten or a hundred others exactly like he described... but hey - I like being exceptional :-)

I've just restored my old wallet.dat from 9 years ago when I was mining and buying bitcoins - it now has all kinds of other balances as well (BCH, BCC, BCD, BSV - at least - as well as original BTC).  I worked this out by using pywallet.py to list all my addresses, and some websites to show my balances.

I no longer have or trust the original bitcoin software that I used to use, and I do not feel like installing anything new (my skin crawls just thinking of all the complexity I'd have to come to terms with to cash-out all those coins and several-dozen wallets).

Does anyone know of a trading exchange or an online web site (trusted!!) which will let me upload my file, supply my key password, and automatically do "whatever it needs to" to efficiently (sensible low fees) let me trade my coins, or, send them to my existing FTX deposit addresses - ultimately - I'd like to use FTX exchange to trade.

Stupid trivia 1: I was buying BTC off eBay for $12, and I refused to pay the extortionate prices of $14 that most sellers were asking at the time... (face-slap).
Stupid trivia 2: I was mining on my top-of-the-line GPU, but it overheated a few times, but rather than fix the cooling [a peltier that worryingly dripped condensate], I simply stopped mining (other-cheek-face-slap).

Hi @passwordnow - I'm talking more about high-frequency trading, not about funding exchange accounts in the first place or anything to do with on-chain transactions.

To be clear - this imaginary meta-crypto-exchange would need to carry a real-time orderbook feed.  For example - If I wanted to buy 10 of XXX coin, and the best price at exchange 1 has only 5 available for sale, and some *other* place - exchange2 - has another 5 for sale (which would be cheaper than buying those remaining 5 all at once from exchange 1) - my order would get split and my purchases made simultaneously across both exchanges.

I guess this is probably a nightmare for any one company to implement - since they would have to have their own balances across *all* supported exchanges sufficient to cover the sum of their own customer balances that might want to trade... and this could easily get "lopsided" making it impossible to place trades for the best prices *every* time there are really good price-arbitrage situations that arise.  It would imbalance really quickly...

Thanks @OmegaStarScream - CoinSwitch comes close, but you have to specifically select just one exchange manually, so it's not going to give users the kind of multi-exchange instant-best-price settlement possible unless you happen to fluke picking the one exchange that's got the best ask order at the instant your trade is executed (so basically - rare).

@tranthidung - BestChange looks pretty cool - doesn't do trading though - it's just a referral site :-(

Coinigy looks almost exactly what I was after (putting aside the major PITA needed to open accounts at all those exchanges myself, and the big problem of having to fund every account at every exchange for it all to work...): @OmegaStarScream - do you know if Coinigy has a means to *automatically* split my order and settle it across 2 or more exchanges so I get the "top of book" (best) on them both?  The entire idea doesn't seem scaleable to me: if they've got order books from (say) 10 exchanges - that's a lot of data, and if they have (say) just 1000 customers, their outgoing data to just those clients is going to be off-the-charts...  at a guess, I'd say that by the time your order hit any exchange, the top of the book's going to have long-gone ?

It *might* be worth investigating the "gamestop" style short-squeeze opportunities that currently exist in crypto?  Read up on how the r/wallstreetbets shafted hedge funds in Equities, then take a look at current over-shorted tokens? (there's at least one I've heard of - you can find these out by looking at how many tokens some exchanges have allowed their users to lend - one in particular has lent more than 100% I think)

Probably the old adage applies - the highest return opportunities will usually carry the highest risk though, so do a *lot* of research first - your £10K profit is always going to be someone else's £10K loss!!

There's lots of exchanges all trading the same things, with their own order-books etc - does anyone know if there's any "meta crypto exchange" out there, where (for example) I can place one order and the meta-exchange will fill it on my behalf using the best matches at *every* exchange it supports (which might be 2 or more at the same time) ?

Kinda like how the "dogpile" search engine from the 1990's used  to(maybe still does) search *all* the search engines for you at the same time, giving you the best results sorted in order on one page?