Hi Mat,
As they say, sharing is caring! :-)
With regards to what I've created, it is a server service designed to manage a collection of wikis (currently limited to 2 per account only for now).
It allows you to save your wikis to the server, or deselect that option in favour of any other saver you have (so you can use noteself inside Maarfapad for example if that is what you want).
It works as a PWA, so you can install it on your android phone as you would an app and it will work just as well (with offline support).
It also keeps an eye on your wikis to alert you whether you if you're about to overwrite the most recent revision of your wiki with an older one that you may have modified offline. This change feed feature isn't available in other services I think.
So using your criteria:
AutoBackup: NO but working on it
Browser: ALL browsers, best in Chrome
Data storage: Cloud and Browser cache (can be disabled on the fly without disabling the plugin)
Dependencies: External Service
Encryption: TW encryption
File or Folder: File
Format: HTML
Mobile First: YES
Muti-user: NO, purely private
OS: ANY
Portable: NO
Version: NO
Works-offline: Oh YES!