Move snap's multi-GB subdir "/var/lib/snapd/snaps" to different partition, then symlink to it?

I have "only" a 64 Gigabyte root partition, /, hence implicitly the /var dir is on this partition, and so is snap's multi-GB subdir /var/lib/snapd/snaps . Snap stores the snap images in this directory. This takes quite some disk space.

I have freshly installed these snaps: boxy-svg, core, core18, core20, core22, eclipse, fx, gnome-3-34-1804, gnome-3-38-2004, go, gtk-common-themes, inkscape, minizinc, postman, powershell, rustup, slack, snapd, tidy, youtube-dl, zoom-client, and they already need 2,7G for a single-instance install. For backups this will increase to 10 GB quickly, because snap stores images of the 2 previous images too, in the long run.

I want to move these 10 GB on /var/lib/snapd/snaps to a different partition, on a different SSD. How can I do that properly?

I've tried by

1. just by stopping snapd with sysctl,
2. move /var/lib/snapd/snaps to a different partition
3. symlinking to that partition ln -s /mnt/big-disk/snaps /var/lib/snapd/snaps
   1, restart snapd

However, this construct does not "survive" reboots (snaps cannot be mounted during startup), and also the snaps cannot be updated easily. As a workaround I've tried scripting commands such as
mount /var/lib/snapd/snaps/inkscape_10426.snap /snap/inkscape/10426
(with /var/lib/snapd/snaps/ being a symlink), but these are a nightmare to maintain, because the release ids such as 10426 always change.