Here's a method - Low competition keywords + parasites
Yep, that's it basically. Design doesnt need to be fancy. I use generate press or stock wordpress 2020 etc. theme with elementor for a bit of styling. They don't have a list but basically they sell direct to businesses and also to other networks like HomeAdvisor and Networx I believe so coverage is very good. Rule of thumb I like to use is 25k+ pop. OR within a major metro area OR has a HomeAdvisor page. For example you can search on Google your keyword + city (plumber Houston), find the HomeAdvisor result (title is something like best 25 plumbers in Houston). The more companies they have the better (more chance of converting your leads to paid ones).
If you build a site and there's no coverage you could always go direct to local businesses or if you don't like doing sales etc. always JV with someone to handle that OR sell the site to a marketer. You can work out the average value of a lead and then times it by your average monthly leads and then by a multiple to give you a rough valuation. Since the site isn't generating income you'd get a lower multiple but you'd still get a decent amount I'd reckon.
Local lead generation is absolutely huge and that's the great thing about it, it's near impossible to saturate vs amazon affiliate sites etc. Think how many cities there are just in the states with 25k+ population, then think about all the services you can do lead gen for (hundreds) that's a load of possible combinations, then add in other countries....
But I understand your comment, it's defo. a issue but no one touches lead gen so it's a huge blue ocean. I have thousands of low competition keywords atm I've stopped looking I've got so many. Big market. That must of been a huge blow though I can understand.