It isn’t difficult for a bad person to remove doorbell to gain unrestricted access to your network. They simply plug in their laptop and off they go! How are you preventing this?
Likely the solution is don’t buy products with hard wired network connections if this is your concern.
To prevent unfettered access to your network via cable would require some heavy lifting, and it is likely not to be developed for so little benefit.
If you want this kind of security then segment your wired network, one for devices, one for computers (or similar). Then buy a firewall product to put between them that prevents access across wired networks, but still out to the internet.
I chose wired PoE because there is no power nearby, poor wifi and to avoid recharging even more batts. Thanks for the interesting ideas. I was thinking of using a Vlan - with extra cost involved for the special switch I expect.