What is the opinion of Reddit about the
StarTech.com DisplayPort KVM – 4 Port – 4K 60Hz – Dual Monitor KVM – DisplayPort Switch – KVM DisplayPort – Desktop KVM Switch (SV431DPDDUA2)?

You’ll have to bite the bullet on either lots of cabling or an expensive KVM switch.

All KVM hardware that can do dual monitors on more than two devices is in the couple of hundreds price range.

You’d need a KVM like this: https://www.amazon.ca/StarTech-com-SV431DPDDUA2-DisplayPort-Monitor-Desktop/dp/B07BJJLRH8

Another option would be to go with may a KVM switch for the surface and macbook hooked up through something like HDMI and the desktop straight through DP. Sort of a hydrid solution.