In practice I feel like it’s a romantic quality, i.e. “since we are both non-binary, I feel we understand each other and I feel especially safe with you, and in fact this type of relationship is the only one I would want”,

That does sound a lot like demisexual to me.

If you call yourself homosexual I worry that some people might misinterpret it and try and figure out a binary gender for you, which is unhelpful.

You could just say you're attracted to other enbies if someone asks? One word labels aren't always the most important thing.