Interesting find on F-Droid:
I was able to install it on my Fairphone 3+ running the latest /e/OS. So far I just triggered it as a regular app. If I get it right, this works as a launcher.
While I have not figured out – for lack of The Switch on any FP other than the FP6 – any specific gesture inside the app to go back to the default launcher, just choosing an app (e.g. Camera) in Fairphone Moments takes you to that app (as intended) and then allows to return to the default launcher as usual.
EDIT: WIth a bit more patience, I was able to get back to the overview of active apps (in gesture navigation: hold-swipe-up from the bottom)