On the last three devices I installed F-Droid on, it was unable to update itself or update apps period. When I hit the Update button it would throw up a generic error message and Googling that message yields hits for multiple F-Droid issues from the past several years.

They have a long way to go before their software is usable. It's a shame because I would happily promote F-Droid to other people, if it worked.