It looks like the Flatpak offers the RazerGenie graphical app for users to interact with, but still requires the OpenRazer software (including kernel module) to be installed on the host system for RazerGenie to interact with.
I definitely agree with @jamesh on the problems associated with having any Snaps which modify the kernel or try to load unsigned kernel modules. I think it could be quite misleading for users.
The ideal “solution” to this (though it’s likely a lot of work) would be for the OpenRazer developers to work towards contributing their kernel driver to the upstream Linux kernel so that software like RazerGenie or others will be able to use the driver in the future without needing to install any packages outside of the confined Snap/Flatpak environment.