strfry always has been a custom database though. Quadrable was just the syncing mechanism and it has been removed in the current strfry version.
While I admire the effort, I think it’s a mistake to build a custom db for nostr. Scuttlebuttl went down that path repeatedly and it never worked out. The reason strfry works so well is that it was the quadrable database first, then a Nostr relay second. Also nostr:npub1yxprsscnjw2e6myxz73mmzvnqw5kvzd5ffjya9ecjypc5l0gvgksh8qud4 is somebody who’s worked on databases for a long time.