You’ll never be able to get a list of channels based off of subscriber numbers because that is private information, the only way to get subscriber data would be to have a user connect to your app and authorise you to view that data, so you’ll only ever be able to sort by subscribers the channels that have connected to your app.
There’s no simple way to sort channels by ascending follower count, you’ll have to make requests to go through 100 users at a time and sort a list yourself.