Yep, the flag is right. Unfortunately the way snap is designed is that they really don’t want you to distribute binaries outside their special snap store, to the point that if you try, they try to scare your users off by naming ‘install outside snap store’ flag as ‘--dangerous’.
Moderation transparency is the building block to what comes next: mod elections. That’s the one piece still in the works, after that is done, I’m going to consider it stable.
When I was first considering the Linux packaging question, I did evaluate AppImage, Flatpak, Snap and plain old tar.gz, with AppImage being my favourite. Unfortunately they are not equally polished and AppImage flat out did not work in a consistent manner across multiple Linux variants. Between the rest, tar.gz was ok, but there are a lot of people who don’t know what to do with it. Between Flatpak and Snap, Snap was the vastly more polished experience for the end user and for me, so I bit the bullet on their non-ideal ‘we want to be an Apple App Store clone’ way of working and went with Snap.