Fossify Gallery on the official F-Droid repo
The removal isn’t directly related to the buyout/fork. Simple Gallery was taken off of F-Droid due to a dependency on the nonfree Google VR being discovered by IzzySoft¹ ². Fossify’s fork has removed the dependent features to be compliant³.
I meant it in the sense they could discontinue the FOSS version and roll their own privative one in its place. They’re “simple” apps after all, wouldn’t be too hard to make a simple clone. What they’ve really bought is a trademark/placeholder (along or not with a company, I haven’t looked much into the details).