When our clients were looking for new software, we could just point them to apps.ubuntu.com/theapp and the would easily understand how to install it using the apt: link .
Giving direct apt:/ links in support emails or tchat is not really and option
Could we discuss this ? or maybe we need a new app:// protocol ( that could be implemented by non snap/apt distro ) that would be launched from a distro agnostic web app store ?
if you go to an app page like: https://snapcraft.io/beebeep the install button will offer you a one-click way to install it on ubuntu systems via the graphical app store and a manual way for all other distros.
if you scroll down to the very bottom of any app page in the snapcraft store you get to instructions how to enable snap support on any supported distro. while an app:// or snap:// protocol would indeed be great to allow one-click installs everywhere, snap support isnt available everywhere by default (like apt support isnt on i.e. fedora, opensuse or slackware) so you will always need to jump though some hoops here … i doubt there is a way around … but i thnk the current setup of the snap store makes this as easy as possible.