It’s easy to hang or attach things on earthbag walls. Simply embed wood poles or blocks between courses of earthbags as you’re building. Some call these nailers, some call them gringo blocks.
I also use rebar a lot to attach things to walls as I’ve explained previously.
[Off-topic but interesting point: The website below has a list of recommended books on adobe construction. Note which ones they prefer and why. They like the books by Paul Graham McHenry, Jr. because they are “excellent in all areas — from explanations of the ‘hows’ and ‘whys,’ to drawings that make clear those explanations. This is the same approach I’ve used on my upcoming earthbag book that SHOULD BE AVAILABLE WITHIN A WEEK.]
Image credit: Desertphile.org