I sometimes watch (in horror) as my nephew uses his Dad's phone to play whatever shallow, glossy muck he finds in the play store. He spends as much time swatting ads, refusing to upgrade to the pro version and hitting 'back' to get out of the play store than playing the games. It's amazing to watch a 6 year old develop muscle memory on these things. I see him swat away an ad almost before I've even noticed that it wasn't part of the game. He has effectively learned to be an ad / upgrade swatting machine. That is the game. Because he has absolutely no "sticking power" with any game. It's the play store / game / ad version of doomscrolling.

I've realised that giving him a reduced hand-picked library of games, with no ads, no automatic prompts to try another game, might be a good idea. These flash games are easily as good as most of the junk I see him play anyway.

I don't mean to sound like the old fart that I am, but you keep describing games in terms of "junk" and "as good as [junk]": maybe instead of giving a bundle of ad-free junk, none of which actually captures his attention and all of which amounts to "doomscrolling," you might consider finding something that does get his attention and occupies it more usefully.

Swift Playgrounds was (is?) ad-free and teaches programming. There are music studio apps that let him compose his own music. Plenty of apps let kids create things actively instead of just playing games. There are also all sorts of non-electronic activities that could occupy his time more fruitfully, but I'll skip over that.

I really like flashpoint but I wish there was a plugin for curation / recommendation. I have an index of games in my head from my childhood and so does my SO. Together we can play the games we know, but have little ability to discriminate between trash and gem. There are simply too many to reasonably pick at random. The old flash sites offered some curation.