Update: after setting `MOZ_ENABLE_WAYLAND=1` globally (e.g. in `~/.pam_environment`), opening links works, so when Wayland gets enabled by default, this issue should no longer occur.
My other problem (the shell not recognizing Firefox as an application) is still blocking IMO, but it's tracked in bug 1530052.
Update: after setting `MOZ_ENABLE_ WAYLAND= 1` globally (e.g. in `~/.pam_ environment` ), opening links works, so when Wayland gets enabled by default, this issue should no longer occur.
My other problem (the shell not recognizing Firefox as an application) is still blocking IMO, but it's tracked in bug 1530052.