Validating Product

IMHO

1. Make a simple landing page with the description of the startup. Even if you do not have the whole thing ready yet.
2. Come up with the pricing. For the time being limited price - %60 (as an example)
3. Create a subscription/form.

And try marketing that landing page, use google, facebook, instagram, and specific niche group/site/forums.

Wait and see if there is any interest from the audience