I live alone, so yeah. I had various roommates when I was younger, My general approach was that if it was just us guys in the apartment, I left my towel in the bathroom and walked naked between bedroom and showering. For roommates that didn't reciprocate, I kept it at that level, which I felt was acceptable incidental nudity associated with male-only habitation. Even roommates that didn't reciprocate seemed fine interacting with me if we crossed paths when I was naked.
I had a couple of roommates who maintained a similar bedroom-to-bathroom only nudity I did have a roommate that was as open as me about nudity, so we routinely just kept the bathroom door open so that the other could piss or use the sink while one of us was in the shower (which had a glass door, so we could see each other and chat while naked and going about our business).
In any case, every male roommate I've ever had has seen my penis many, many times