If you configure a minimal profile such as this:
Then the details should come from /usr/share/xsessions/foobar.desktop.
This mostly works, except for the displayed name of the profile. Instead we show the folder name ("foobar") in this case.
Can be easily tested by removing the "name" settings from one of our predefined profiles.
Fixed and works now. Tested on RHEL 8 with GNOME profiles.
Tested on Fedora 33 with GNOME profiles and a minimal custom `.desktop' file as seen below. Everything seems to work as intended!
> [Desktop Entry]
> Name=A really good name
Clarification to comment 3: Tested on Jenkins build #2029.