Notes are simple text files (.txt or .md), so you could use the Nextcloud desktop client to synchronize your Notes cloud folder, and edit them on your PC using your favorite text editor.
Notes Nextcloud app don’t support offline editing and synchronization as itself, so it has to be done on client side.
Hello.
I personaly use this solution on a daily basis to sync notes between my phone, Linux box and Ruindows pro laptop without any issue (editing individual note files on desktops through a text / md editor, like Sublime Text, Kate, … what you like).
(except that the NextCloud client on the phone is a pain to use : need to explictly sync any folder each time needed, rather than doing it just as the desktop clients, I mean … automatically).
I left some links in Sync eCloud notes on Evolution - newer Evolution can do Notes with .md extension too - or the simple gnome-notes (bijiben). Evolution is a bit of an underdog for what it can do.
I run it on Mac and LInux laptops. Combined with NextCloud Notes app (the upstream that /e/ have forked to make their own Notes app) on my phones, it means all my notes are available on all my devices at any time. I recommend it!