Thanks. I tried that using:
smb://[NAS NAME].local/[FOLDER NAME]/
I copied that path straight out of the Files app. Unfortunately it does not work. There is a yellow exclamation point flag next to it that says "This is not a valid option."
I ended up installing the rpm-ostree version of Firefox, which accesses my Nas just fine for proton drive uploads. I do hope to eventually figure out how to do this with flatpak/flatseal, but this works for now at least. I appreciate the help!
