I would have a question about how I could resolve a user logging in to my website with Twitch, asking my app for permission to see which channels or in this case, see who is subscribed to my channel and how many months to subscribe ? Is this possible at all in any way?
Thank you in advance for your answers!
Authentication docs start here Authentication | Twitch Developers
Then use the oAuth token with Get Users Reference | Twitch Developers to get the user
Sounds like you want to get all channels a user is subscribed to. This is basically not supported. There is Reference | Twitch Developers but you need a pair of ID’s you can’t get “every” a user is subbed to.
Using an oAuth token the represents you (not a user) Reference | Twitch Developers
This information is not in the API
You can get it if/when a user shares their resub via EventSub or PubSub or Chat. So refer to those docs for the relevant events/data