avaiable-regions endpoint, you an get a list of Data Center Locations that are available for the sites within your company.
You can obtain the company_id from MyKinsta > username > Company settings > Billing details.
The company_id is also shown in the URL in MyKinsta, for example in the URL https://my.kinsta.com/?idCompany=bdd25d71-5706-4890-870f-1adda17c505d the company_id is bdd25d71-5706-4890-870f-1adda17c505d.