You'd need some snap store to be able to install it without using --dangerous flag. Snapcraft.io is Ubuntu's (and most popular one), though that might not work for you if you want the download to be available exclusively from your own website.

But then again, if it's on Snapcraft, you don't need to worry about distributing updates to your users.

Might I suggest distributing your app as an AppImage? snaps require the snap package manager (snapd) to be installed on your system. AppImages, on the other hand, run out of the box after a chmod +x.