It's probably too late for you to see this, but if anyone else is wondering.

DeepRim is actually a much older mod than z-levels.
I say this, because it's also much more simple in how it functions.
It basically creates another colony, just using cave generation settings.
And places a fast travel spot where you put the mineshaft.
As far as the game sees, it is just a separate colony.

So I don't believe pathfinding is really possible, without a huge amount of work.
And let's be honest, the pathfinding in z-levels never really worked 100%.

One thing that could improve things is if there were a scheduling system.
Where you could schedule them to go down and work until a certain time, then come back up.
Which would help a lot with all the fiddly work you have to do day to day.

It is ok i was just curious, in my experience the pathfinding in Z levels was flawless. Even raids tried to get to you on the 2nd level if you were down there. Only thing that didnt work was they werent hauling. They always only carried 1 stack of items to the other level. Im baffled anyway that noone continued that mod. It was super famous and almost every other mod out there got a continued, except this.

TLDR Sounds nice but difficult and currently there are bugs that could use fixed

I'm just a nobody but I've seen several comments to this effect scattered around. I was getting ready to put in a round of bug reports and small feature requests regarding this mod, I might brainstorm ways to implement this sort of behavior but it seems like it would take a lot of work.

I can imagine the ability to allow/disallow pawns to enter mineshafts (like how doors are)... pawns could check whatever layer is selected in the nearest mine for work to do, or maybe to reduce calculations you could assign one or more pawns to specific mineshafts and they would prefer working in there over working on the main map (?).
Idk, I'm just spitballing.

Anywho, before anything this is implemented we first need to have the mod not send pawns and items into solid concrete, because that's a thing right now if you have more than one mineshaft (and a bunch of other simpler behavior, like integration into chemfuel / nutrient paste networks)

There's a reference to "Pocket maps' in 1.5 so there might be a chance for that in the future. If someone tried to implement it right now it would be kinda jank.

I hope this can be done someday :<

You can use skipgates for this im pretty sure. Its a workarround but works great. You need the skipgate mods that allow hauling for that tho.