This is not like the PS3 generation where the Cell processors had massive untapped potential, and were priced well below market for that kind of compute.

The PS5 (and its Xbox counterpart) is more-or-less just a modern budget gaming PC with a little bit of special sauce. The only advantage here is that component pricing may have been locked in before the RAM crisis.

CPU is a rather weak Zen2. If that still appeals to you, instead purchase a BC-250 mining board. It's a PS5 reject and nearly all of them can be fully unlocked for all 40CUs and 8 CPU cores. They are quite popular right now for building Steam Machines and all the hacking has been done with replacement BIOS mods.

Not worth it. It's basically a knee capped Ryzen 3700X with less cache. You can get a better CPU for less money. The GPU performance is still alright but it's not good at non-gaming tasks as it lacks cores for ML tasks.

Nah you're better off just buying a PC. Gone are the days where you were getting amazing hardware for the price

Beware that you need a hypervisor exploit to run Linux. And these are incredibly rare. But, there was one patched very recently on firmware version 14.10

So, if you buy a PS5 now, you should be good

It is indeed a good time. Latest firmware patched the recent exploit, but most or all boxed PS5s in stores should still be on old enough firmware. This will not be true forever. Beware of used units since they could've been updated already.

Wouldn't make much sense since hardware-wise you're very much paying for the GPU power and not CPU power, which isn't gonna help you much at compiling.