Tips for growing SaaS business targeting 5.4m micro businesses?

Does anybody has tips for growing a SaaS business by targeting micro business owners cost effectively? Which advertising/social channel works best for acquiring micro and small business customers for a SaaS business?

This month, I have launched AXSAR Solo - 'One app to run your small business'. The idea is that small businesses can use ONE app to manage all aspects of running their small business (customers, sales, help desk, tasks, invoices, files, notes, diagrams and more). https://www.axsar.com/axsar-solo/

I have got good feedback from startup founders, other product managers and colleagues. I have few actual small businesses/startups who are using the platform, and they love it. The challenge I have is how do I find and get several hundred/thousand small business owners to try the platform, and provide genuine feedback around product experience, pricing and features?

On Betalist we got few hundred visitors to the site, but only a few dozen signed up. Apparently many of those users are not small business owners. I have to still try ProductHunt, have been keeping it for the end to improve my pitch in the meanwhile and was waiting for creation of AXSAR Solo promo video which is ready now.

I have tried Facebook/Google but the paid ads are way expensive as AXSAR Solo is partly a CRM. Currently I am trying Reddit Ads.

In UK alone, there are 5.4 million micro businesses (less than 10 employees).

Ideally I want to target these micro businesses as the product will simplify running their business (one app) and also cut down on their subscription costs. Micro businesses wouldn't have to deal with integrations across different systems.

As a solo tech founder, I have found a process to develop and bring a new product to market rather quickly, but now the challenge is how to find a repeatable and sustainable process to reach those micro businesses cost effectively.

Any suggestions/articles regarding these questions will be highly appreciated.