There are two ways to obtain subscriber data.
One is via a Token representing a user and you lookup if a user is subscriber.
user to channel
Or you obtain a token from the broadcaster and lookup subscribers that way round
channel to user
Both ways have merits.
First you need to do have setup a oAuth handler to create the authentication keys you need
Whether thats a User Token or a Broadcaster token, it doesn’t matter The flow is the same. Just the scopes are different
once you have a oAuth key, you can then perform the subscriber check using either of the two references I linked to earlier. And then cross reference that with your storage of minecraft names and update the Whitelist accordingly additionally cross checking with yggdrasil if you want.
If you didn’t want to custom a solution, there are a few Minecraft mods that’ll do it for you, but this can be done via Vanilla without any need to use Mods.
Not on the forums no, we have a looking for devs on the Twitch Dev Discord