How to validate an idea for Esports?

I'm trying to validate an idea for an app in the gaming industry targeting esports. There are millions who play worldwide so how would i validate it and figure out the right country to start with given that there isn't much searchable data to go on? I can only find rough player counts per country after googling but no deeper information. Do i need to validate it on a country by country basis or is there a quicker way/other solution i should consider?

Would really appreciate advice on this, thank you.