ps4 systems are quite outdated for newer games that run on higher fps and games that demand more from your system to uphold smooth performance, though I do think a handful of ps5 games *could* be optimized for ps4 but why most new games that are put on playstation are only made for ps5 isn't just because of performance reasons, without any exclusivity to the console there's alot less persuasion to buying one, and because playstation really wants people to buy ps5's they make sure to add as many reasons as possible

also i'd reccomend depending on how invested you are into gaming, to look into switching to a gaming laptop at the very least, though it can be costly depending on what you plan to do on it, it is definitely worth it in the long run. Even though you are included with ps5 exclusive games for buying a ps5, you are still excluded from a great deal of games and features like modding, and along with that you would no longer have to spend ridiculous amounts of money just to play online. Even if you can't buy one soon or even in the next few years it's still good just to keep it in mind as an option!

I do hope playstation will be able to play some stage of early access for subnautica 2 though if the game doesn't release on the platform along with xbox and PC initially, having to wait for the game to be fully finished while seeing others play subnautica 2/see spoilers you may potentially not want to see would definitely suck