M-Bus interface built-in?

Hardware Questions and Recommendations
1

Has anybody a recommendation for an openwrt router with built-in M-Bus interface ?
I know about Teltonikas TRB143, but that is running their own variant of openwrt.

2

Wired or wireless? Or a variant like M-Bus-over-Infrared my power meter uses?

I'm not aware of any such device, but you can probably plug a USB converter into any device with a USB controller.

3

Wired. USB-converter I do not like, because of the "flaky" connection, sometimes.

4

If you can't find such a device running OpenWrt, I can recommend solutions based on ESP32. I read my smart meter using an ESP32 with LAN interface, powered by ESPHome.