Pipo
1, download Obtainium. https://github.com/ImranR98/Obtainium
The instrustions to install are written.
2, go to the main page of whichever github project interests you (with research and prudence)
3, scroll to the bottom and discover the 'Releases' button. Long press and copy the link address.
4, Go to Obtainium app press the add app button at the bottom. Paste the previous link in the top field.
5, tap add.
This method is the best to ensure updates.
You can install directly from github too, by simply tapping that releases button from step 3 and following the instructions, but then you must find a way to keep your app updated manually.