Maybe you want a non deb specific packager. cpack (cmake packager) can generate Windows, OSX, DEB, RPM and simple archives. There is also fpm that doesn't support Windows, but supports plenty of packet managers. And possibly many others.

AppImage, FlatPak and Snap may actually be worse in that regard, because they are like other distros you have to take into account. So now, you may have to do all of them: deb, rpm, flatpak, snap, appimage, tgz, whatever that's on Windows and OSX, maybe a Docker container too, app stores and mobile stuff, and upload to some npm, maven, crate.io,... It makes generic package manager even more important.