Assuming you had no social media with any significant following or any online presence, how would you get a stranger who could actually benefit from your product to see it?
My experience has depended on my relationship to the product I am building. If it is for users in a community that I am a part of already, I am definitely looking. Otherwise, I have to figure out where these people are. Either way, I believe the term is "lead prospecting." It can actually be interesting even to an engineer, you can kinda fold it into your process, it helps you focus on what you are building if you use it that way.
When you say "lead prospecting," what did that actually look like in practice for you when you were starting from zero? Like for me so far I feel I think too much of how to optimize whatever it is I'm building (which is the relative easy)