Nice! This is actually exactly what Portabella (https://portabella.io) started out as around 7 months ago.

I found that LocalStorage isn't reliable enough to keep all your important stuff, so my thought was to encrypt everything client side and store in LocalStorage + a database. On session startup you just check the lastEdited date of the LocalStorage version vs. the database version and take the data with the latest.

That way it's still offline first but you can also access your data on different machines.

Not trying to plug Portabella too much but I followed this logic and thought, how can I now allow people to share data? What if I give them different views? How about notifications? Pretty quickly I had fleshed out a full product.