demm i think your confusing AppImages with Snaps, AppImages are distro agnostic aswell. As they state on there own website: https://appimage.org/
" Download an application, make it executable, and run! No need to install. No system libraries or system preferences are altered. Can also run in a sandbox like Firejail
Arch Linux CentOS debian Fedora openSUSE Red Hat Ubuntu
Distribute your desktop Linux application in the AppImage format and win users running all common Linux distributions. Package once and run everywhere. Reach users on all major desktop distributions. "