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.

It probably isn't helpful, but updates do work for me on the ancient android phone I've got apps on (Markor, Simple Gallery Pro, NewPipe). Maybe they've fixed it?

That's odd. I've never had an issue with F-Droid over many years and across many devices.

The issue you describe is may be caused by the Android ROM on the phone. I've seen it work without issue on Motorola and Pixel phones, but struggle on OnePlus.

I highly recommend Neo Store. It's a drop-in replacement for f-droid that leverages the newer Android API for seamless updates. Been using it for months happily.

There's a difference between manually confirming updates and manually installing the update APKs. Having to go through the "install", wait 10 seconds, "Ok" process for every single app you want to update is a terrible experience and is the main reason half of the apps on my non-rooted phone are outdated.