Yes. I would also say it depends to the extent of one's agoraphobia. If you can learn to deal with things, then yes, it's workable. As Fande_Strellow mentioned, you have to constantly pick up feces, deal with not firm stools, give food rewards, and fish things out of their mouth, and other things that are just things you have to do as a dog owner in general.
The worst part though for the germaphobe in me is my guide dog laying on the floor while i'm class, in a restaurant, bathroom, etc and just them walking through all those areas. You have to contend with all that and the germs from that, but it's not a big deal and regular grooming and occasional useage of baby wipes takes care of this.

You HAVE to pick up and throw away feces. You also will be hand feeding rewards to your dog and pulling things out of their mouth if they are a retriever. You will need to pet and groom them and take care of their messes. Lots of dirty work that you are signing up for if you want a guide dog.