I'm on Ubuntu and mostly use debs (apt), I'll use Snaps if that's the easiest way to get an update. I use Appimages for some ephemeral stuff or when that's the only way developers release it (some 3d printing stuff). I haven't installed Flatpaks at all because it doesn't jibe with the distro overall.
Debian: probably, yes.
Ubuntu derivatives such as Mint, Zorin OS, and ArduinOS use Flatpak instead.
Others, such as Asmi and Linux Lite, remove snap and offer the user the option of adding it back if they wish.
The first version with snap as standard was 16.04 in 2016:
https://ubuntu.com/blog/canonical-unveils-6th-lts-release-of...
However Ubuntu Core, its immutable distro built entirely from snap packages, was launched in 2014 and there was a Core version of Ubuntu 12:
https://old-releases.ubuntu.com/releases/ubuntu-core/release...
There are about half a dozen cross-distro packaging schemes for Linux, including Nix, Guix, AppImage, Flatpak, Snap, and 0install.
However two are mainstream and supported by large vendors: Flatpak is from the GNOME organisation and is backed by Red Hat and Fedora, and Snap is a Canonical project and part of Ubuntu, the single most widely-used distribution by a considerable margin.
Ok, I do have one spare Linux laptop in my garage that I barely use, and I'm pretty sure how ever I installed Chromium used snap.
Flatpack is useful for the few ones that aren’t or for actively developed apps that get new useful features frequently.