Audience and access are not the same thing
Founders confuse "I have no audience" with "I have no way to reach buyers." They are different problems. Validation only needs access: a way to get in front of people who have the pain and ask them about it. You can get that access through communities you did not build, cold outreach, and a tiny ad budget. The audience question only matters later, when you are trying to sell at scale.
Borrow audiences instead of building one
Go where your buyer already gathers and post or reply there. Niche subreddits, Slack and Discord communities, Facebook groups, Indie Hackers, and industry forums all let you reach hundreds of the right people without a single follower. Read the threads first, find the recurring complaint, then ask a genuine question. You are renting attention, not earning it, and for validation that is enough.
Cold outreach and paid traffic do the rest
If posting is not allowed or the niche is quiet, message people directly. Twenty to thirty thoughtful one-to-one messages to people who clearly have the problem will get you real conversations. To test whether people will act and not just nod, point a small ad budget at a landing page with a clear call to action. Even fifty to a hundred dollars of traffic tells you whether the promise lands.
When having no audience actually hurts
An audience is not needed to validate, but it is a genuine advantage for distribution once you launch. If your whole plan depends on "I'll post it and they will come," no audience is a real risk you should price in now. The fix is not to stop validating. It is to start building a small audience in parallel while you test demand, so you are not starting from zero on launch day.