Connect RAK7258 to ChirpStack v4?

I am currently my RAK7258 (Firmware: 1.3.6_RAK b150, Mode: Packet Forwarder) with ChirpStack v3 and I would like to upgrade to ChirpStack v4? In the LoRa Network settings I can only select ChirpStack v3.

Is it compatible with v4 even when using v3? Or will there be a firmware upgrade in the near future to support v4?

I can confirm that RAK’s v3 integration is incompatible with Chirpstack v4 (TX does not work, and so nothing can join). Why they don’t just run Chirpstack’s own gateway bridge is beyond me…