Is it safe to remove snapd and snap-store when using gnome?

snap-store consumes 200MiB memory and 50MiB+ disk I/O (for half a day) in the background, and snap consumes lots of disk space. I haven't used them manually but it seems that they provided gnome and gtk:

Name               Version             Rev    Tracking         Publisher   Notes
core18             20210611            2074   latest/stable    canonical✓  base
gnome-3-34-1804    0+git.3556cb3       72     latest/stable/…  canonical✓  -
gtk-common-themes  0.1-52-gb92ac40     1515   latest/stable/…  canonical✓  -
snap-store         3.38.0-64-g23c4c77  547    latest/stable/…  canonical✓  -
snapd              2.51.3              12704  latest/stable    canonical✓  snapd

(output of snap list)

Will removing snapd (from apt) and snap-store (probably from snap) make the life more difficult, e.g. having to reinstall the whole gtk & gnome?

As of August 2021, you can safely remove snap-store. The only impact will be that you no longer have access to the eye candy of the Snap Store.

Alternately, if the problem is size and bandwidth, consider helping to reduce them. Snap-store is forked from the upstream gnome-software application. The gnome-software developers do not intend the application to be annoyingly large nor bandwidth-intensive and welcome code contributions that will reduce those footprints

Removing snapd is also currently possible without destroying your desktop (exceptions: Ubuntu Core and snap-based Kiosks). Your Gnome desktop is not provided by those snaps. However, you may lose access to some applications (like Chromium) that are provided only by Snaps.

Again, snapd is open source. The snapd developers welcome code contributions that reduce footprint, improve performance, and enhance security.

In future releases of Ubuntu, the Ubuntu developers plan to Snappify some core features (like CUPS and the printing interfaces) to reduce their maintenance burden, so future readers of this answer should check carefully (like you did) to see what software Snaps provide.

snap-store its just a way of installing software. by default it makes a partition for every installed application just to insolates them.

from my experience on ubuntu when i was installing apps from snap they were running extremely slow and had a bad experience from performance point of view. so instead i installed software from the publisher or from apt package manager.

remove snap forever with no problem. this answer explains that you can do that without having problems.

For recent versions (not sure about the old versions)

It wouldn't break your system, you can still run GNOME, but any apps installed with snap wouldn't work, Including the software stores, as they are all(edit: all of the stores that come pre-installed in Ubuntu) based on snap.

Oh and these

core18             20210611            2074   latest/stable    canonical✓  base
gnome-3-34-1804    0+git.3556cb3       72     latest/stable/…  canonical✓  -
gtk-common-themes  0.1-52-gb92ac40     1515   latest/stable/…  canonical✓  -
snap-store         3.38.0-64-g23c4c77  547    latest/stable/…  canonical✓  -
snapd              2.51.3              12704  latest/stable    canonical✓  snapd

are all for snap,

• gtk-common-themes is for snaps to use some common gtk themes, as snaps are sandboxed
• gnome-3-34-1804 is for snaps to communicate with gnome
• and the rest for snaps as all the packages you have listed here are.

If these are the only snap packages you have installed, it means that nothing is affected except the software store, your system will run totally fine.