There will be a new gallery app for GOS some time
https://github.com/GrapheneOS/Gallery
It is a fork (copy) of this. You can try it now if you'd like:
https://github.com/IacobIonut01/ReFra
Keep in mind, once the GOS gallery app comes out, you can't just replace it or move over your saved settings or AI picture embeddings easily if at all. But what's a few setting toggles, right?
Some of the default apps are outdated, lacking features, and should be replaced. The default files app is useful for viewing folders that need higher permissions.
Consider getting a better app for: gallery, files, calendar, and--if you want to integrate birthdays or export backups--a different contacts app. There's some suggestions on this site.
For files I've heard of fossify file manager and amaze. I like the former.