Thanks. It's odd that the system file explorer is not an option. That leaves a question but not one either of us can answer.
I have Total Commander and it's good to know CX Explorer is worth a look.
I am left with my outstanding quandary (not Joplin-specific though related) whether ANY app given permission to see the file system COULD see all or any file/s it chooses to and therefore whether to (attitudinally) trust such apps and whether to (functionally) comprehend that capability/vulnerability which can only then be functionally mitigated.
The biggest players' central revenue streams overtly relying on harvesting data and erasing the very notion of privacy from the minds of the masses. For our convenience.