I saw this TFTC post on X about Google Play Store rules for software wallets (including, it seems, non-custodial wallets), but they didn't have a source.
In an post on their Policy Education and App Requirements page, Google has this article "Understanding Google Play’s Cryptocurrency Exchanges and Software Wallets Policy." In it, they say
To ensure a safe and compliant ecosystem for users, Google Play has established specific guidelines for the publication of cryptocurrency exchanges and software wallets. Cryptocurrency exchanges and software wallets can only be published in the following countries/regions if the app complies with local laws and industry standards.
When you scroll down to the table, you see this next to the United States:
The developer must be either (a) registered with FinCEN as a Money Services Business and with a state as a money transmitter or (b) a federal or state chartered bank entity.
Also: The Rage now has an article on it: https://www.therage.co/google-play-store-ban-wallets/