I don't think it's even possible to cover every sport. Nevertheless, as this project gets bigger, it'll probably attract more attention and smaller sports can try broker a deal with them in order to get their game more popular. It's a matter of quality over quantity.
I don't understand how bets can make smaller sports significantly more popular.
Yes, because you can bet on some game only when it gets popular and appears at betting platforms. It doesn't work in the opposite way