The login looks alike cryptomator.
The use of webDAV looks alike cryptomator.
The structure (de flated) of the folder structure looks alike cryptomator
The INABILITY of android app to provide “document provider” alike ability is alike cryptomator.
I am finding alternatives among the existing solutions,
cryptomator is now 1.6.x, and document provider seems is to be planned to 1.9.x.
It’s already years long.
Personally i wont wait, i’ll try find other alternatives, even non-open source.