Adding crypto related apps seems a good start to me for PlayMarket. Don't worry for hard time at the beginning, they will be aggressive on marketing
They will need something that differentiates them from the PlayStore and sticks out. Crypto related apps could be an idea with a good potential to grow when the crypto scene becomes mainstream.
But now big smartphone companies have their own app market , It' s very very hard to convince them to do it
IN my opinion it's not gonna happen, android has play store and that's it, I don't wanna talk about apple because you already know. Maybe if windows was still a thing, but anyway it was a crappy mobile OS