I have been searching for the same and did try carnet and joplin. But now i found a new contender. Quillnote https://qosp.org/ downloaded it from fdroid. It looks lite keep/carnet and syncs to Nextcloud. 5/5 😁
QuillNote is pretty good. It allows organising your notes into different 'notebooks'. Markdown support, image attachment support are big positives. There's also the option to sync it with NextCloud, if you wish to do that.