I've been down this rabbit hole as well. Many of the sync projects seem great at first glance (and are very impressive technically) but perhaps a bit idealistic. Reactive queries are fantastic from a dx perspective, but any of the "real" databases running in the browser like sqlite or pglite store database pages in IndexedDB as there are some data longevity issues with OPFS (IIRC Safari aggressively purges this with a week of inactivity). Maybe the solution is just storing caches in the users' home directory with the filesystem api, like a native application.

Long story short, if requirements aren't strictly real time collaborative and online-enabled, I've found rolling something yourself more in the vein of a "fat client" works pretty well too for a nice performance boost. I generally prefer using IndexedDB directly— well via Dexie, which has reactive query support.