GNOME software requires a default route to work
I'm using GNOME Software in Fedora 38 within Qubes OS. It's a kinda special setup as the Fedora 38 is a template and doesn't have any network interface attached,
dnf works by using an http proxy routed through the hypervisor to a dedicated network VM.
When using no default route and a dnf proxy, when looking at the program "Ardour", clicking on "install" make the button switch to "cancel" and nothing happens for hours.
pkill gnome-software gnome-software --verbose &> gnome-software.log
I found a hack consisting of adding a dummy device with a fake route, GNOME Software started working after running the commands:
ip link add dummy0 type dummy ip link set dummy0 up ip addr add 192.168.0.1/24 dev dummy0 ip route add default via 192.168.0.2 dev dummy0
Another hacky solution is to attach a network device but block all the network traffic.