xr-hardware install via deb

(my name)@(my name)-pc:~$ sudo apt install deb http://ppa.launchpad.net/monado-xr/monado/ubuntu impish main
[sudo] password for (my name):
Reading package lists... Done
Building dependency tree... Done
Reading state information... Done
Package main is not available, but is referred to by another package.
This may mean that the package is missing, has been obsoleted, or
is only available from another source

E: Unable to locate package deb
E: Unable to locate package http://ppa.launchpad.net/monado-xr/monado
E: Unable to locate package impish
E: Package 'main' has no installation candidate