Was largely asking for all the people looking for specifics, since people were asking, and vague advice isn't very helpful when first starting out with this stuff. Like broadly, I've had luck with Linkedin messages for b2b and SEO for consumer, but mostly after the product is in an ok place. The initial users can be tough to find.

But sure, I'm working on things for parents/students, home buyers, and DIY heat pump installers.

Off the top of my head (don't expect any revelations here, but mostly for people wondering how to approach this type of thing for the first time):

* Parents/students hang out at schools and are probably a good referral/recommendation crowd

* Home buyers are looking for mortgage comparisons on Google (but that's probably a terrible strategy, since this is a highly lucrative segment to market to, so you should expect high customer acquisition costs)

* DIY heat pump installers will probably look at ads on /r/DIYHeatPumps