You will lose access to any software installed via a snap package. Snap software is "containerized" (to varying extents depending on the install mode and permissions) so you would lose access to "snap" containerized software speifically. There are other ways to run containerized software you wouldn't necessarily lose access to though are not installed or used by default and that can also be used at the same time as snap packages (e.g. flatpak, docker, etc).

There is some software installed by default on 22.04 by snap that has no Ubuntu-provided alternative "deb" package. This includes firefox and the "Ubuntu Software" store app (installed by default) and LXD (not installed by default, but if you want to use it, there is no deb package). If you're not using any such snap software, it may not matter. In some cases you may be able to install software through some other non-snap method from a non-Ubuntu source (e.g. you may be able to install firefox using the standard linux installer, though I have not tried that).

With regards to the Ubuntu live kernel update feature, this is powered by the 'canonical-livepatch' snap. When you run "ua enable livepatch" it installs the snap. Without snap, it won't work, hence you won't get live patches. Livepatches are not automatically enabled by default for a standard install on your own hardware, you need to attach it to your ubuntu account with "ua attach" and then "ua enable livepatch" (it's free for 3 personal machines and requires a paid subscription otherwise). You can read more about that at https://ubuntu.com/security/livepatch. The snap package is the only canonical-livepatch client package hence if you removed snapd you would lose access to use livepatches.

Disclaimer: I work for Canonical (Ubuntu).