NostrNet "Note extension" just for posting notes is coming. 

It will also function as an offline note app simultaneously. Notes will be stored in your offline local storage unless you explicitly choose to post them to Nostr. 

It's designed to be very lightweight, and most of its components work offline, ensuring it won't crash.
https://i.nostrimg.com/357f147f832f050f93fbead7a9c92ca4697ecced8ab743f7d72a0161455b2dab/file.jpg