The extension does appear in the settings menu after "settings" and after "help" on my Samsung galaxy tab 10a, so to a certain extent you could say that it works on firefox android. But when I try to save the tabs and try to open them after restarting the app, I only see a gray list and my saved tabs just don't appear at all. Also when tapping on the empty gray list, nothing opens. Giving each tab collection a name also doesn't seem to solve this problem.

No support for pinned tabs in a session. No support for multiple Firefox windows.

I don't want to be forced to name each session, a date and time should suffice.
Also, it keeps opening the session in a different window which is unacceptable.

This is more a lackluster session manager than a tab manager. It only allows you to save tabs of the current window not even all the windows of the session and that's all.