Looking for research ideas to add an exhaust fan in my bathroom. The room is small. Behind the door is the toilet, then a small sink cupboard, then a tub/shower with a window that opens by sliding upwards.

I don't think there's any electricity past the sink. Walls are lath and plaster.

And I'm not super skilled, but also not completely inept.

Are there any minimally invasive approaches for me to look into, or is this a full on contractor situation?

Thanks for any ideas.