Indeed it now seems that there is no restriction at all any more. The profile does not even mention /home, and yet I can browse there, also in /selinux (which is also not mentioned in /etc/apparmor.d/gdm-guest-session). The profile didn't change in ages, so I suspect it's either a regression or a behaviour change in apparmor. Need to investigate further.
Indeed it now seems that there is no restriction at all any more. The profile does not even mention /home, and yet I can browse there, also in /selinux (which is also not mentioned in /etc/apparmor. d/gdm-guest- session) . The profile didn't change in ages, so I suspect it's either a regression or a behaviour change in apparmor. Need to investigate further.