Hmm you are out of luck there then.
Twitch’s API when it comes to subscriptions is geared to “channel subs” and “is user subbed to $given channel”
Theres no official end points for pulling out the friends list either.
And doing it the “get followers and then testing sub” won’t work either as you’d run into rate limit issues under helix I imagine.
The closest you get is https://dev.twitch.tv/docs/v5/reference/users#get-user-emotes which’ll give you the emote set ID.
And then use this API https://twitchemotes.com/apidocs to get the “Emote Set Mapping”. Bit of a hack but thats what you could do right now…