For some background see https://github.com/systemd/systemd/issues/29768


systemd-networkd and NetworkManager both support ID_NET_MANAGED_BY,
which is a udev property that can be set for a network interface and
denotes which program is supposed to manage said interface.

https://www.freedesktop.org/software/systemd/man/latest/systemd.link.html#Property=1
https://www.freedesktop.org/software/systemd/man/latest/systemd.network.html#%5BMatch%5D%20Section%20Options
https://networkmanager.dev/docs/api/latest/NetworkManager.html → Udev
Properties

WDYT about adding support for that to ifupdown?