The quality of games on Google Play is much worse than what is available on Steam and the variety of titles are much greater on Valve's platform too, with far less in the way of microtransactions and other exploitative behaviours (though Steam isn't free of this) and a back catalogue stretching as far back to the mid 2000s.

Both Microsoft and Sony AAA titles, most third parties publish there and most indie games release there first. Steam's library is unparalleled in the industry, the only thing it's truly missing is Nintendo's games.

Ok, but the market is absolutely flooded with exploitative stuff, laden with micro transactions and a trickle of miniscule rewards, in attempt to addict the user, rather than genuinely provide enjoyment.

How do you even discover the good games that are worth being played on Android?

I'm aware of https://nobsgames.stavros.io/ , but I'm afraid it might not be extremely up-to-date

And also, I think that Google Play has a much bigger problem than Steam, when it comes to old games being made unavailable (think EA's zzSunset stuff)

Total sum of complexity and quality is comparable.