How does that rich text work for Kind 1? I was musing about sticking out-of-band formatting information into a tag.
In the next update of the NostrNet Notes extension, I'm adding advanced text editor for writing notes and articles.
You can draft that offline or publish it on Nostr.
Standalone link: https://notes.nostrnet.work/
Discussion
Some elements work as markdown those will be available, for offline all elements will be available. I also have to make slight adjustments.