Getting the number of subscribers in Python

Personally I do a fetch weekly (or daily) against this API ^^ and then use Webhooks to keep up to date with changes.

https://dev.twitch.tv/docs/api/webhooks-reference#topic-subscription-events

And I store the list of subscribers in a database or redis (depending on the use case)

And I count my internal list for count purposes

What ever works for you. I use a mix of JSON file, redis, and structured database depending on the use case.