What KVM (+ possibly other hardware) do I need

I currently jump between a couple of Mac and Windows laptops on my desk. Whichever one is the ‘prime’ machine at any time is connected to a Dell TB3 (100W) dock which in turn is connected to a 4k monitor and wired keyboard.

Technically the monitor has 65W power delivery and 2x USB A ports, but it doesn’t seem that powerful or stable - whereas with the Dell, everything is rock solid.

I haven’t really needed a KVM, as moving a cable between laptops has been pretty frictionless. The added complication is that I may soon be adding a desktop machine to the setup.

I want to be able to keep the 100W PD for the laptops andhave the keyboard follow the monitor. Is the easiest option to buy a the L1 combiner, and just plug the TB3 dock into that as needed? I assume I won’t fry it by connecting it to something looking to deliver power to the output side?

Is there a L1 KVM that will do everything in a single box?

ETA; one of the laptops is horribly locked down, so a software solution won’t work.