Is there a way to make the PS5 compatible for PS2 games?

My best guess is you're talking about actual PS2 discs, not PlayStation Now or whatever. The answer is no, unfortunately. The only PlayStation consoles that have backwards compatibility are PS2 and PS3 because they both support PS1 discs.

Aside from PS Now, no. 

But alternatively, you COULD just buy the PS4 remastered version of it, provided it’s compatible with the PS5. Many of the PS4 games are, so chances are, many of the remastered versions can just be played straight up in the PS5. 

That’s likely the closest you’ll ever get to true backwards compatibility unless if Sony provides another method to allow you to play those PS2 games on the PS5

No, the only way you can play ps2 games on ps5 is by subscribing to psnow.

Not possible unless Sony adds that feature which I doubt they will.

no, there isn't