Yes it is, but f-droid isnt as recommended as getting it from the source. F-Droid is fine but Obtainium with direct from github is better.

Except Accrescent isn’t owned by GOS or affiliated with them. Its just a recommended app store by GOS on top of GOS’ own app store and in general for people not on GOS. Ironfox is also available directly from github and Obtainium can be used to install and update Ironfox from github along with other apps directly from github.