Only the very basics, more to come.
For now:
$ busctl tree org.freedesktop.network1
└─/org/freedesktop/network1
└─/org/freedesktop/network1/link
├─/org/freedesktop/network1/link/1
├─/org/freedesktop/network1/link/2
├─/org/freedesktop/network1/link/3
├─/org/freedesktop/network1/link/4
├─/org/freedesktop/network1/link/5
├─/org/freedesktop/network1/link/6
├─/org/freedesktop/network1/link/7
├─/org/freedesktop/network1/link/8
└─/org/freedesktop/network1/link/9
$ busctl introspect org.freedesktop.network1 /org/freedesktop/network1
NAME TYPE SIGNATURE RESULT/VALUE FLAGS
org.freedesktop.network1.Manager interface - - -
.OperationalState property s "carrier" emits-change
$ busctl introspect org.freedesktop.network1 /org/freedesktop/network1/link/1
NAME TYPE SIGNATURE RESULT/VALUE FLAGS
org.freedesktop.network1.Link interface - - -
.AdministrativeState property s "unmanaged" emits-change
.OperationalState property s "carrier" emits-change
