Obtainium allows you to install and update Apps directly from their releases pages, and receive notifications when new releases are made available.
Read the Wiki
Currently supported App sources:
Open Source - General:
Other - General:
Other - App-Specific:
"HTML" (Fallback): Any other URL that returns an HTML page with links to APK files
Limitations:
For some sources, data is gathered using Web scraping and can easily break due to changes in website design. In such cases, more reliable methods may be unavailable.