I usually visit the source code page (almost every time on GitHub) and check the timestamp of the commits, how many issues are open, how they are handled, etc.

I usually visit the source code page (almost every time on GitHub) and check the timestamp of the commits, how many issues are open, how they are handled, etc. The usual indicator of a project being alive. The number of downloads is less important. Often there are plenty of equivalent proprietary apps on the Play Store with 100'000+ downloads and I'm going to F-Droid because I trust open source apps more. 10 downloads would be enough.