I'm running the latest version of the 'devel' brunch successfully on a Fedora 33 VM as well as a Debian 10 VM on top of Qubes OS.
I did try to open Leo's own outlines from the GUI-menu, with the following result:.
* Open 'CheatSheet.leo' - OK.
* Open 'LeoDocs.leo' - Not OK. - See "Log-004".
* -> file not found: /home/user/PyVE/GitHub/Leo/leo-editor/leo/doc/html\conf.py
* Open 'LeoDist.leo' - OK.
* Open 'LeoPy.leo' - Not OK. - See "Log-006".
* Open 'LeoPyRef.leo' - Not OK. - See "Log-007".
* -> can not open /home/user/PyVE/GitHub/Leo/leo-editor/leo/plugins/trace_keys.py
* Open 'myLeoSettings.leo' - OK.
* Open 'quickstart.leo' - OK.
* Open 'scripts.leo' - OK.
* Open 'leoSettings.leo' - OK.
* Open 'unittest.leo' - Not OK. - See "Log-012".
* -> no command function for 'open-unittest-leo'
You might consider fixing those glitches.
With kind regards,
Viktor