I don’t have much to say about the move to the App Store except that given that there is apparently a market for a standalone paid indie photo browser, the Mac market may be more vibrant than popularly assumed.
There are fives of lattes per month to be made in this market, it's blowing up! ;)
Looks like more of an organizer than browser. There's definitely a need for image browsers considering how bad Apple's Preview is for that. I'm still using my old and trusted Xee3 for any sort of image browsing on macOS because of that.
Well, preview is not a browser so it’s not surprising (unless you’re thinking of Photos, which is ok but not great).