Consider this use case:

1. The user has a wifi capable Linux gaming handheld (like the RG35XX Plus or the Miyoo Mini). These are not capable of running browsers.
2. The user has purchased a couple of NES games here.
3. There's a client app on the device, which at first startup shows a URL (with a QR code).
4. The user reads the QR code, logs into itch.io, gives OAuth permission to the app (I guess people prefer not to enter passwords with a D-pad and ABXY buttons).
5. The client app queries the list of purchases, and can filter for game roms, displays them.
6. The user selects a game, the client app downloads the ROM file, and puts it in the correct directory.
7. The user can play the purchased ROM on the device

Of course the authorization needs to be done only once per device, so the next ROM download would just involve firing up the app, and selecting it from among the purchases.

I could start working on such a client, but the itch.io API does not allow me to download games if I understood the docs correctly.

This could also mean PortMaster being able to download game data files for ports, then maybe PortMaster could feature “ready to run” game demos (like a shareware game), and the full game data could be purchased on a phone and downloaded via PortMaster or the game itself.