To all of IH, How do you guys validate your ideas? | Problem: Eye Strain

Hi,

I have a chrome extension idea that I would like to validate. The idea is not innovative, I found many extensions but found it to be just too not so friendly or lets say, UX friendly.

Idea:
-> The Problem: Eye Strain:

1. Personally have eye strains due to continuous screen time, being a software (gaming) dev, sometimes crunching 12-14 hrs a day.

2. Paid doctors a visit, gets eye medication for a few months, they get alright but a few months later again have to pay visit.

3. Any Ophthalmologist (Eye Doctor) I visit no matter what area, or clinic or hospital, the most generic advise I get is to get off the screen every few minutes + reduce screen time (that's not really an option for a developer) + dont work in dark lights, especially late night crunches with dim lights (which is my goto flow state).

-> Solution to my Eyes Strain:

1. Came across this 20/20/20 technique for eye strains, on a few google searches for eye care medical websites.
2. Went to chrome web store and found a few but too laggy/ poor UX/ just not up with it. The idea is not innovative, but I am neither satisfied with whats on the market.
3. Half way into creating my own chrome extension, reminding me to take 20 seconds break after every 20 minutes.

-> Benefit of this Chrome Extension:

1. I can not only save the paid visits to eye docs, but my eyes in the long run.
2. The Technique seems to be convincing. You may google yourself.

Idea Future:

1. Personal Use: No matter what happens, I am going to have to create it for myself anyways, since I am in the habit of losing track of time when at work/ or even just randomly on screen.
2. Others: I believe there might be some going through the same issue, but main dilemma is my own eyes strain fixation at the moment.

However, If this is released for the public:
Q1. How would you go about this and validate this and are there any specific websites that seemed to have worked for you/your product/your service?
Q2. How do you come up with this type of service pricing? I believe since it's a chrome extension, the pricing should be really low, even lesser than a cup of coffee per month, which is around $2?
Q3. I don't want to complex this up, an easy to go reminder, or a dumb assistant that whose sole purpose is to remind you to take breaks every 20 minutes and come back after a few seconds is all.

So what do you think about this?

Thanks for your time.