"When sharing a note in Lightning Experience, you can provide Viewer access only. There is no Collaborator access.
Notes doesn’t support simultaneous editing, and this restriction prevents multiple people from editing a note at the same time. If multiple people change a note at the same time, they overwrite each other’s changes."
However there is a workaround - each enhanced note is stored in ContentNote. We can query it and open in classic by pasting the Id in URL and then add users as Collaborator. Now added user can edit this enhanced note.
- I created an enhanced note with name "Test Note".
- Queried it dev console [SELECT Id FROM ContentNote WHERE Title ='Test Note']. Got the record id.
- Switched back to Classic and then pasted in url - it opens up the content note in classic
- Added target user as collaborator using sharing setting button.
- Logged in as Target user and now able to edit note even in Lightning experience
This is just a POC, we need to find out some way to reach the content note without querying record for general user - a button or a link.