Related question to people building local-first - what size of db is too big? I always see examples doing todo lists etc which seems perfect for this. But what about apps with larger databases. When does local-first no longer make sense?

I wonder the same thing, especially thinking about local-first image storage.

Iirc there are different limits on IndexedDB sizes depending on the browser/platform, and the tighter limit is around 1GB. But I would love to hear from people that ran into those limits.

It really depends on the browser. There's a good breakdown here:

https://rxdb.info/articles/indexeddb-max-storage-limit.html

Our dbs range from hundreds of MB to gigabytes.

This is discussed in the blog post. A lot of offline-first tools fall apart at this scale.

Maybe duckdb-wasm is the answer (also check sqlRooms github)