Bathroom drain in my way

Bathroom drain in my way - HELP!

Cut open the wall (1'x3' space) of my 2nd floor bath to split the single light into two.

Problem is that there is the 2" PVC sink drain line when the box will go, and assuming it goes up to the roof?

What options do I have? Thinking of cutting drain and zig zagging around the
box. Smart? To code? Any other options?

Help please?

If you are going to "zigzag" use 45's and not 90's.

Depending on the type of light fixture you plan to use you might be able to install a pancake box on the outside of the wall .

vent

As long as it is just a vent, and it appears to be the case, you can do it anyway you want to using any fittings you want to. It is only air.