I use the NextCloud Notes app ( which is the app from which /e/'s default app is forked) and the NextCloud syc client from F-Droid, It works just fine, and I can access my notes from my phone, from the web or from my computers.
I just installed Carnet from F_Droid, but I couldn’t get to to sync with any of my NextCloud accounts (eCloud and OwnDrive.com)