For android : Basically almost all app from SimpleMobileTools, a few version right before it was sold (to a company in a controversial city)
For desktop : some kde app that works both for windows and linux (I used windows for now) like Okular and FileLight (though this one isn't so much daily basis)
and for both I used LocalSend
iirc the purpose of mintest itself is to be a stepping stone to make other game, but if people are having fun playing it as it is then I'm very glad