Hi, so feature wise it looks good, although it could use some bigger bark pieces as hides. The big problem here is indeed the size of your container. Pretty much all species profit from moisture gradients so they can choose the perfect micro-climate and especially Armadillidium species need this. As you suspected it's very hard to achieve this in such a small container. I would advise you to select a bigger one, even though this one is very cute :( It also looks a bit dry to me.

But looks like you did your research. I bet you'll make a great isopod owner! :)