Why not just put the release URL in the bar? Or are you strictly testing the search feature?
Tried to set up the Grand Slam of excellence using Obtainium.
Maybe I'm not the smartest user, but it took me over 5 minutes
(Note: I was trying to find the Github release of Amber, not Fdroid, I should have previously unselected those sources from the options)
https://cdn.satellite.earth/633e02861ed2d18123424422779a5eae22659510b2fd251a8cc7cdd192cfe37a.mp4
Discussion
Because I would have to find the URL somewhere, I would still need to search, only outside the app
Obtainium is good because of the massive catalog but the UX is terrible