How to validate your business idea before launching a digital product?

There are numerous ways to validate an idea for a digital product, and some of them are described in this article https://www.mobindustry.net/blog/idea-validation-for-a-digital-product-importance-approaches-and-criteria/.
I brainstorm ideas and validate them through tools like a Validation Board and a Validation Canvas. These tools allow you to gather and systematize all your assumptions about your product and the market’s reaction to it.

A Validation Board allows you to define your hypotheses, track your assumptions, and reasons why your product might be a good fit for your target audience.

What tools and methods do you use on a daily basis and why?