Trying to find a docking solution for FW13 AMD and MacBook

I’m trying to find a docking solution for my FW13 AMD and my MacBook (on loan from my workplace).

In order of priority, here are my goals:

  • Using the same hardware for both FW13 and MacBook,
  • I want to connect two monitors to my laptop,
  • via a single USB-C cable,
  • and charge it via that cable too.

The FW13 has USB4 ports and the MacBook has Thunderbolt 3 ports. I’m unclear on whether the MacBook is compatible with a pure USB4 hub or if it needs TB.

MacBooks are not compatible with docks that use MST (multi-stream transport). It also sounds like AMD USB4 can only handle one DP stream, for which MST is a workaround.

My current attempt is this:

  • TB4 hub with 2 downstream TB ports.
  • Hub has PD, this works fine.
  • TB->DP adapter in one port connected to monitor. Result: monitor is fixed to wrong resolution (640x480) and makes loud clicking noises.
  • HDMI expansion card in one port (because I don’t have a TB->HDMI adapter) connected to monitor. Result: monitor does not connect; FW13 touchpad disables while expansion card is connected.

All of the above works perfectly on the MacBook.

Does anyone know how I might achieve a single-cable dual-monitor docking solution for the FW13 AMD and the MacBook at the same time?

Imo it’s more needing the second DP channel is a workaround for not supporting mst but I suppose that’s a matter of perspective.

Maybe one of the docks that has both mst and multiple dp channels and then plug in the second port on the mst and the second dp channel into the second monitor and hope it switches correctly.

While I am convinced mst is the better solution for single cable multi monitor I don’t quite understand why amd didn’t put in the second dp channel, while there is precedent for single dp thunderbolt ports (weirdly from apple) it still makes compatibility confusing and turns a thunderbolt compatible port into an almost thunderbolt compatible port.