AWS publishes its own IP range: https://docs.aws.amazon.com/general/latest/gr/aws-ip-ranges.html
I was wondering if I could obtain the same for Starbucks establishments.
The end goal is to ban Starbucks customers; I already have a ban on Mac OS user agents which is close.
There's no reliable public list of IP addresses for Starbucks Wi-Fi, nor is there any reliable way to determine if an IP address corresponds to Starbucks Wi-Fi.
After Starbucks (at least in the US) switched from AT&T to Google for Wi-Fi service, Google has been providing the service via any available ISP, whether Google owned or not.
For example, the local Starbucks Wi-Fi provided by Google is run on a Comcast Business cable connection. There's no way to distinguish its IP address from any other Comcast Business customer.
Therefore, in order to ban Starbucks customers, you will need a fairly large IP address range:
If you block this range, it's guaranteed to block all Starbucks customers. (And everyone else.)