I find the only app in F-droid very lacking, and the couple I tested from the PlayStore lacked many of the technically available controls you can see on IRDB, Global Cache, JP1, etc.
I am seriously surprised there is no open source Android IR remote app that can truly put everything to shame, given that the info is out there. I may contact a friend of mine for a new Android app...
I downloaded DivestOS IR remote app and I can use it no problem on my Unihertz... I don't think it's locked up at all.