I'm using Emacs for something similar.

This works because Emacs can open .gpg files. It will decrypt them on opening (asking for your password) and encrypt on saving. This is very powerful in combination with Orgmode (.org), or any other module that provides auto-folding.

So I open my .org.gpg file and everything is folded. Then I search for what I need, and only that part (containing some secrets) is unfolded.

Of course, this is no substitute for a proper password manager, but proved to be useful a lot more often than I initially thought.