I tried to look for a similar call for helix, but I did not find it. Has it been implemented?
You’d have to use V3/V5 for “what subscriptions does a user have”
New API - Get Broadcaster Subs
New API - Get User Subs
Get User Subs doesn’t work with a user token to get the subscriptions a user has.
You have to use v3/v5 to get the subscriptions a user has.
Get User Subscriptions
Gets broadcaster’s subscriptions by user ID (one or more).
Get User Subs lets you perform a broadcaster_id/user_id key search when you have a broadcasters token.
OP specifically asked about subscriptions a user has. Which is NOT in Helix
I didn’t realize the OP was being that specific.
Will it be implemented in helix in the future?
Yes. Before v5 is removed
Interpreting the title. It’s from user to broadcaster, not broadcaster to user, which is all thats in helix right now.