The file browsing is fully offline supported (as in the files get synced locally). We also allow text search offline, but smart search is not yet offline (we need to embed the search prompt), however, we would like to support fully offline use soon!
Many tools offer offline file browsing and full text search. Anything from midnight commander to Alfred to ripgrep.
I think the valuable and difficult thing is high quality, fast, offline semantic search, including indexing (so my files don't go to your servers -- that's an immediate no-go for all the important industries).
I've tried my hand at this a couple times and it's hard! But really hope you succeed, because it would be a big game changer in how we organize and use information. Every company out there would buy this immediately.