How do I validate my idea?

Hi Indiehackers 👋

TL;DR: I want to know if the users will pay $1 for 10 minutes of high-quality web page-to-audio conversion. Google ads don't give good results so far.

Longer version:

I'm building an app (primarily for myself), that will allow users to convert their read-it-later blog posts and articles to speech with much better quality than the market currently offers. More details are at article2audio.app

I opened the app of everyone two weeks ago, and I've been running ads in Google search for queries such as "article to audio", "blog post to speech", and a couple more synonyms.
This doesn't yield any good results -- 20 users signed up; one added a blog post and converted it to audio.

What else can I try to validate if the users will pay?

Thanks!