You can just use your own password manager and it wouldn't automatically do anything to apps on reinstall, right? Or a physical notebook, maybe.
A physical notebook is so easily lost I wouldn’t even consider it.
Just search for keepass in the app store (Keepassium, KeePass Touch, Strongbox, ...)
(I use KeePassDX from F-droid it does not have network permissions)
Frank Dux was a fraud! :)