Eumenia As I desribed its very easy to get reproduction by at least 3 parties
To what extent is it happening?
I think a week or so ago I checked for a few random apps whether or not F-Droid felt that their build was reproducible
(de0u). What I checked was absolutely not a random sample, and absolutely was too small to draw conclusions from. But the results didn't seem overwhelmingly great to me.
Personally I was not encouraged by not finding a single inventory across the whole site of which apps do/don't have reproducible builds. But perhaps people who find F-Droid's investment in reproducible builds to be encouraging could check to see how many of F-Droid's builds are believed by F-Droid to be reproducible.
If it's hard for F-Droid to get right, perhaps that's because they aren't good at it, or perhaps it's because it's not "very easy" after all.