looking at Taz Pro twin head I wondered what the endstops are for the 2 hotends… mechanical (switch) or optical or hall effect.
I’m not sure what you are looking at.
Here’s the full assembly instructions for the dual-head (except for the cosmetic cap that goes over the top): https://ohai.lulzbot.com/project/dual-extruder-assembly/quiver/
The dual-head on the Pro has 2 actuator motors that lift/lower the nozzles so that the inactive nozzle doesn’t drag on the part … but those aren’t end-stops. I wonder if that’s what you are seeing?
The X-axis gantry also doesn’t use end-stops on the Pro. It uses “bump sense” (load on the motor) to detect when it hit the travel limit.