Flatpak gThumb access to Autofs CIFS mount points (set under /var)

I installed SilverBlue 38 and thus had to change the way to configure my NAS CIFS mount points.
Previously I used to rely on /etc/fstab on Fedora (requiring chmod u+s mount.cifs) or Ubuntu.

I moved to autofs - systemd is another option but I hate it - I find it awkward & too heavy.
With Silverblue & autofs, it seems mount point can be done only under /var .
I created a directory named /var/nas - I tried to use /home (which points to /var/home ) and /media with no success.
The issue is that Flatpak programs (such as gThumb cannot access /var by design if I understand things correctly. So I cannot browse pictures from my NAS anylonger.
Any work-around or idea to solve this issue ?

Edit : found a work-around :

ln -s /var/nas $HOME/nas

And granted through Flatseal Gthumb access to full home directory