Awesome app. It is somehow not listed on android-foss list so maybe someone didn’t know about it.
Obtainium allows you to install and update Open-Source Apps directly from their releases pages, and receive notifications when new releases are made available.
GitHub page: Link.
Have you tried F-droid alternatives like Neo Store or Aurora Droid? Maybe they fit your needs.
I’m using NeoStore, it’s not bad, but the problem is when I get a new smartphone: there’s no way to export the list of the app that it installs, while with Obtanium it’s possible