If you're doing something because you're hoping it becomes important enough to generate money, just say that. That's not volunteer work though. It's actually entrepreneurship. That's actually a good thing. And I wish more open source people would lean into it.
If you want people to pay for a certain future to exist, that's cool too. That's called philanthropy. Also not the same as volunteering. For instance, you really have to tell people a story about what that future looks like.