WireGUIde requires a fairly recent version of network-manager, and of course wireguard support. For example, while wireguard is available from buster-backports, network-manager for Debian Buster is too old (1.14.6). WireGUIde is known to work on Debian and Ubuntu versions with network-manager >= 1.22.10. That means that it will work on Debian Bullseye, Ubuntu Focal and Ubuntu Groovy. Other distros have not been tested yet, but should work if the software running is sufficiently new. WireGUIde has also been successfully tested on Fedora 33.
It is no longer recommended to install using pip or the previous created appimage, since this project uses dependencies that are not easily packaged using universal binaries or python packaging (infact appimages and pip project has been removed). Instead the native debian/rpm package is recommended: