Sounds like they want everyone to download directly from the Play store, and not in a way they can’t control?
Same trend as the official OS only apps, overzealous ‘Play Protect’, etc.
You can still use Files by Google to share Android applications in a similar manner. Under Categories, go to “Apps” and then the overflow menu for what you want to “Share.”
A lot of other apps still support it, including FOSS ones, unless the play app did something extra?
For example
- SD Maid SE:
App Control
>Export App
- Kvaesitso: long tap > 3 dot menu >
Share app
- F-Droid for all of their apps
While I haven’t tested these extensively, you could give them a try (both are foss):
First one is designed for managing / cleaning up app storage. Second one is a launcher, so it might be a bit janky if all you need to do is transfer an app