Not getting email replies for discovery emails

I am working on several micro-SaaS/Indie ideas for small businesses but I am having trouble getting them to reply to initial discovery emails. I sent them emails describing problems I want to solve for them and inviting them to talk to me in exchange for free lifetime access.

I sent two email campaigns to two kinds of small businesses. Both times, I describe the problem I would like to solve and say I am building a product intending to solve it, then ask for 20 minutes of their time in exchange for free lifetime access. I find the ones with active Instagram accounts, hoping they'd be more open. I haven't had one response so far.

I guess I could take it as signal that my ideas are bad, but it would be nice to have more explicit feedback. Even an email response saying "this is stupid and has literally never been a problem" would be welcome. Is there a better way to access these businesses?