personally, i have both a PSP and a PSVita, i ended up getting a PSP 3000 because PSP and PS1 games don't look that good on the PSVita, they render at their native resolutions and then it just gets stretched to fit fit PSVita screen, it's playable, put the loss in image quality is baffling (specially in 3D games, on pixel art games like FF1 to 4 you basically can't tell the difference), that's why i keep using my PSP for PSP games when i don't just emulate them on my Deck, although on the vita, you can use adrenaline to use the second joystick of the console as a dpad, so some games like Monster Hunter play WAAAY better on it, due to basically play like modern MH, no clutch claw grip breaking your hand in order to move the camera and the character at the same time, so you lose some, but you gain some.
PSVita is a great handheld, specially if you mod it you can bypass completely the crappy proprietary memory cards using a small adapter called SD2Vita (uses the game cartridge slot, there is a variant for the 3G models of the PSVita 1000 that replaced the sim module for an SD card one), overall in terms of options and potential the Vita es way better than the PSP, but it has some drawbacks like the ones i mentioned at the beginning.
Now, on this day and age, you have 100$ devices like the retroids capable of so much more, you're looking for raw power at low cost, that would be the way to go, that, or a Steam Deck, another option that comes to mind is getting a Nintendo Switch, and modding it, but that's a complete different world because you can only softmod the first models of the switch, personally for my Switch i had to solder a modchip, which can be expensive (i did it myself because i have tools and the experience), a Switch has emulators for basically everything nowdays, the scene still going strong on it, and in fact you can even install linux and use it as a PC, or android and use it to play smartphone and PC games natively with varied degrees of success, there's some videos around where people play WoW on the Switch.
If you can afford it i would tell you to get a Steam Deck and fill it with a bunch of emulators, it's a powerhouse, from NES to WiiU, from PS1 to PS3, very few games will have trouble running on the Deck.
But yeah, unless YOU REALLY WANT A VITA, i wouldn't get one today, comes with a bunch of compromises, at around 100$ you can get a used nintendo switch for the same price or a bit more, and do so much more with it, moreover, the vita is out of production, so spare parts are even more rare by the day, soon it will be hard to fix any fault with it, unlike the PSP i don't see the movement in looking for replacement solutions like the screen kits for the PSP 1000 and 2000 models... the more worry inducing part is the battery, those die, and i unless you decide to do some redneck modding using a smartphone battery replacing the original one could be a nightmare soon...
I love the vita, it's been my favorite portable system since i got one 6 years ago, but i have to admit, that in this day and age, has some compromises you might not be able or willing to do, specially if you have a money tight situation as it seems in your case, and looking at the current portable landscape i would keep the PSP, and save for a Steam Deck, since that's probably the best bang for buck you can find right now, with the refurbished sales Steam often does, grabbing an led or oled 512gb model or the lowest possible storage model and then upgrading to a 1 or 2 TB SSD would be the thing, i think.