We have building an IoT device using a minnowboard that has 2 ethernets ports.
We need to let our snap configure the ethernet ports. One is externally connected,
and the other side is connected to custom hardware on a static IP.
We would like the auto connect the network-control for this snap.
network-control is a very powerful interface and this snap sounds very specific to your device. I suggest instead of issuing a snap declaration to auto-connect the interface everywhere, you instead use your gadget snap to auto-connect the interface on your devices. The feature will be available in 2.34 (so be sure to use the core snap from beta or edge), see Gadget snaps for details.
-1 to auto-connect