This idea of a dual ethernet PoE passthrough ESP32 device is not new, but after 5 years of no one making this device available, I am moving forward.
I have the capability to design and fabricate very nice PCBs that can fit into readily available enclosures and mounts.
My roadblock will be getting assistance from someone to get the chip to supported by ESPhome ethernet. The KSZ8863RLL was already supported in esp-idf years ago, so it should be doable.
I am looking to design this as a switch first, with an esp32 attached second. The reason I am designing it this way is so the switch functions even if the esp32 aspect does not function or is misconfigured so devices down the line are not disconnected.
The switch will bootstrap into simple switch mode. This may actually simplify getting the chip supported, hopefully.
Does anyone have any thoughts on this, or can suggest someone who would be willing to assist in getting the chip supported in ESPhome?
At first I though you were talking about a power switch, and then when you started talking about Ethernet I though maybe you are talking about a network switch.
Are switches with POE common? I believe they are. Ones with an inbuilt ESP32 as well? Not sure they are. Is this what you are proposing?
HomeAssistant struggles to support everything at the application level. Asking it to support things at the level 3 layer may be stretching your friendship and possibly out of scope.
You may find it is a niche market for your device, and ESPHome is probably not the method I would use to write firmware for a network switch device. The device you mention only supports 100mBps speed, so time has possibly passed it by, and MicroChip probably have a SDK, evaluation board and application notes that could be used to roll your own combo pack.
ESPHome have a Discord server. There’s a developers channel there. It is very active. I suggest you start by chatting with them about how your proposal will fit into the project. Invite link: ESPHome