Ask HN: How do you promote your service online?

I made a product in the crypto field, a service I know people need and does not exists on the market right now so I know people want to know that service now exists. And they hopefully want to pay for it.

But most social platforms prohibit self promotion to cold audience. Eg. Reddit, most discord servers. Cold emailing is prohibited by law.

How do you promote for a new product when you don't have network?