I have never seen a Micro-Trains car with a see through walkway. You should look at either Gold Metal Models or Plano Model Products to see if thery have a stainless roofwalk to fit the car you have in mind.
You might also check to see if anyone still has asny JnJ parts left. They had a lot of roofwalks at one time.
The only MTL coivered hopper that I am aware of having a see through walkway is the PS-2.It is not etched metal (I’m told it is Laser cut wood)but it looks very nice,The rest of their covered hopper walkways are simply molded plastic.
As for a comparison to IM’s metal walkways ,MTL’s stay flat .
The PS-2 4427 is a fairly new MTL casting and has a see through roof walk.As far as I know it is the only covered hopper MTL does with this style of roofwalk.
InterMountains covered hoppers have etched metal roof walks.I do believe there are other model makers that have them too.Plano has a fair selection of aftermarket etched roofwalks and Gold Metal Models also.