Workarounds / alternatives for the limitations:
1. You can link between Notes. On a note, click collaborate icon, click add people, in share options tap icon for Copy Link, and then dismiss the To: dialog with the “Copy Link” text top right. Paste that link in another note. Now they’re cross-linked like a wiki. Instead of doing all this, create/use a shortcut.
2. Use Exporter: https://apps.apple.com/us/app/exporter/id1099120373?mt=12
3. Protect any given note with a key. The note data is encrypted, and stored encrypted anywhere it is stored.
4. Surely changing the background is an optional feature, not a limitation? There are a ton of features Notes doesn’t have, but not having them may not be in the “limitation” category.
// FWIW, I mostly use Ulysses.