[wluu]

There's AltStore, but it's obviously not as straightforward as the Apple one. https://altstore.io/

Came across it while following the development and distribution of iSH (https://ish.app/), which has now made it into the main app store.

Prior to publishing to AltStore, iSH was only available on Test Flight, which has a limitation on the number of users who can join (10,000). So they'd periodically have to kick inactive users off the TestFlight so others could try it.

[camhart]

AltStore requires a software developer to set it up and use it. Not anywhere close for non-tech people, let alone elderly.

[wluu]

Yeah, I said it's not straightforward.