App to Validate Customer Interest in Business Ideas

Have had this idea in my head for a while. Let me know if there's already a solution that does this or if it sounds interesting to anyone as this is the target audience.

I want to build an app to gauge customer interest in various business ideas. Use case, say I have 5 potential ideas for SaaS apps, but before I invest weeks and months of time into any individual idea, I want to validate there is substantial interest in the market for such a service.

Conceivably, it would go down like this. A template builder helps you generate a quick landing page with product info, pricing (to validate people actually want to pay for this), and an email sign up. Analytics are baked in to track the number of visitors vs signups.

The business creator finds where the target audience hangs out (Facebook groups, etc) for each business idea and does some tasteful promotion of the site/service. The biz creator can analyze which of the ideas generates the most hits/sign ups.

More so than just a landing page template builder, I see a site that allows multiple tests under one domain, such as:

biztester.cookiedelivery.com
biztester.jewlerystore.com
biztester.cloudcdnservice.com
biztester.realestateportal.com

Then the business creator can log into their account and see a dashboard with all the analytics (visits/signups) from one source.

This idea keeps popping into my head because such a pain point as an indie developer is finding product/market fit. Does anyone provide this service currently or is anyone interested?