I tend to prefer "file centered" apps, there's some cool one you'd use with Syncthing?
My favourite is KeePassDX; I would love a notes app with a 'material you' UI.
Well, since you love KeePassDX as me, I started to use KeePassDX as a "database of notes".
Under Root, you can create categories by adding 'Group's.
Inside each group, you can add an 'Entry' (a note).
each Note, will have a sub Category (Title), subject of note (User name), url and the note itself (note).
you can also add tags to your notes.
Give it a go, you'll be surprised how well this works, finding/searching for whatever is there.