Ask HN: How to bootstrap marketing without being spammy?

I just launched a kind of niche product. It does solve a real problem and there is a market with some established players already, but this technology is an improvement. But I am starting from zero.

Other than getting lucky and blowing up on HN or product hunt, does anyone have any other repeatable demand generating suggestions that don't feel so spammy (like messaging a million people on linkedin)? I'm just trying to get the first couple of trials and testers to see if I could even get one sales meeting.

Is the only way to just keep banging on your drum? I understand successful marketing won't happen overnight.

Any suggestions, tools, or processes I could follow? I'm willing to pay for some courses or books if they are highly recommended.