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.
While I agree the apps shouldn’t be removed, updates aren’t just about features. Updates fix bugs, security holes, and improve performance. I’m notsaying these apps in particular have issues, though what app doesnt, just pointing it out in general.