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On Lexaloffle, under the web player of each game, there's a pink cartridge icon. The image that opens is the cartridge - download it and load onto your favorite emulator.
Itchio also has a bunch of those games, and iirc they have a tag for PICO-8 games as well.
Also also, iirc the cartridges can be converted to Android's native format. And I'd need to confirm, but maybe HTML too, which if possible, would probably let for the game to be run on JoiPlay.
Via browser on desktop or mobile, you can play a nice selection of featured carts here: https://www.lexaloffle.com/bbs/?cat=7&carts_tab=1#sub=2&mode=carts&orderby=featured
Another list here:
https://nerdyteachers.com/PICO-8/Games/Top200/
I believe there are other ways to store and play the carts across other platforms, but you'll need more help than I can give you on that stuff.
I don't know if there has been a better way since 2024 but take a look at this guide by Russ: https://retrogamecorps.com/2024/06/21/native-pico-8-on-android-guide/
and games, you would get from for example itch.io or the internal browser called splore.