Support for simultaneous Ethernet (HA connection) and WiFi Station (IoT device polling) for isolated networks

[chaichuk]

Describe your core improvement

It would be great if ESPHome could support simultaneous operation of Ethernet (e.g., LAN8720) and WiFi Station mode.**

Specifically, I would like to configure ethernet as the primary connection for the Native API (Home Assistant), Logging, and OTA, while simultaneously using wifi to connect to a secondary, isolated network (like an IoT device acting as an Access Point) to poll data via http_request or modbus.

Current limitations

Currently, the Network component appears to prioritize a single interface for connectivity. If ethernet is configured, it is difficult or impossible to maintain a parallel wifi client connection to a different subnet.

Users cannot easily bridge an isolated device (that only exposes a local WiFi AP) to Home Assistant without using two separate ESP devices bridging via UART or ESP-NOW.

Technical benefits

Hardware Efficiency:

Removes the need for two separate ESP32 boards to bridge a single device.

Connectivity:

Allows integration with "stubborn" IoT devices (EV chargers, solar inverters) that act as WiFi Access Points with fixed IPs (192.168.4.1) and cannot join a home network.

Reliability:

Users can keep the stability of a wired Ethernet connection for Home Assistant while still accessing WiFi-only sensors.

Additional context

Real-world Use Case:

I have an EV Charger that only broadcasts its own WiFi Access Point with a fixed IP (192.168.4.1) and exposes a JSON API. It cannot connect to my home router.

I want to use a single ESP32 with Ethernet to:

1. Connect to Home Assistant via Ethernet (for reliable control and telemetry).

2. Connect to the EV Charger via WiFi (to poll the status JSON).

Currently, I am forced to use two ESPs or hacky C++ workarounds to bypass ESPHome's network management.

Here you can find my project that bypass current limitation - https://github.com/chaichuk/EVcharger-to-ESPHome