It's unclear from this article, which, to me, seems to be more about appeasing big game makers. This part talks about the third party app stores briefly.

...Google’s announcement also includes details on how third-party app stores can come to Android. Third-party app stores will be able to apply to the company's new "Registered App Stores" program to see if they meet "certain quality and safety benchmarks." If they do, they'll be able to take advantage of a streamlined installation interface in Android. Participating in the program is optional, and users will still be able to sideload alternative app stores that aren't part of the program, but Google clearly has a preference. Changes the company plans to make to sideloading later in 2026 could deliberately make the process more difficult, which might force developers to apply to Google’s program.