Most third party software for Sony consoles is either CFW or home-brew that runs on CFW. It's not too hard to jailbreak a Vita on the upside, though it's harder than it is to jailbreak a PSP (because Sony's private key for PSP FW updates got leaked, which means that CFW for PSP is indistinguishable to the PSP from an official FW update).
Much if not all of it is already saved, though storage requirements get progressively harsher with each generation. You can fit every Atari 2600 game ever made on a floppy disc, every NES or SNES game on a CD, PSP UMDs typically held around 1GB each, while the current Switch E Shop (don't have a number for how many/how large are any physical only releases) requires a ridiculous amount of storage (like, US only end of 2020 in compressed format clocking in at 5.66TB). Google actually changed their policies for shared team drives because people were replicating complete game collections for PS3 and later consoles and it was becoming a problem.
Yeh, I know. I'm a bit of an emulation enthusiast and have spent a significant amount of time and effort dumping my own games, including PSP and PS3. So I'm familiar with CFW. But don't have a Vita, so I'm not in the know about its particulars. But yeah, I know a lot has already been saved. As mentioned, there's a fair bit of overlap between the piracy and emulation scenes. But there's still gaps, more obscure games and a lot of DLCs. Hence my hope the community will try to fill in those gaps. Which will eat up a lot of storage. I should know, my console game backups takes up about 2TB. Almost twice that if I include pc games. And as you said, that's only a fraction of what is out there.
So long as the battery works then the console is good then? I wonder how hard those would be to replace.
Replace a cmos battery? Easy. Cheap too. Couple bucks gets you a new battery from the nearest gas station or wherever you can get batteries, and they last a good while. But this battery powers the internal clock of the console. The moment you remove the battery to replace it, that clock loses power, stops working. Putting in a new battery will probably get it to run again, but the time you spent replacing will not update by itself. So the next time you boot up your PS4 it will notice the time is wrong and try to fix this by calling home to Sony to authenticate.
But when the console can't call home anymore, the time stays wrong. Which does not seem like it matters much, but it does. Because trophies require an up to date clock to work, while trophies working is in turn a requirement for games to work. And pretty much all PS4 games have trophies, whether digital, or physical.
This is why the PS4 becomes a timebomb the moment Sony turns off the PS4 servers. From then on, all PS4s remaining lifespan becomes whatever the cmos battery's remaining lifespan is. Unless Sony releases an end-of-life firmware update that removes that requirement. Or you have the skills to replace the battery without breaking the circuit as 09philj said, or you know how to hack the clock.
I wonder if PS5's have the same requirement within.
Chances are good that yes, it does. It's a quick, easy and cheap solution. Hence why it's used so much. Technically, the same can happen to any pc, because those also have one of those batteries on the motherboard. But it's not as big a problem there, because pc being what it is, there are simply more avenues to fix it.