The following works for me for Azure Devops Services (cloud):
curl ... https://vssps.dev.azure.com/acme/_apis/graph/users
However, for my on-premise installation I'm getting 404 for all following options:
curl ... https://tfs.acme.com/_apis/graph/users
curl ... https://vssps.tfs.acme.com/_apis/graph/users
curl ... https://tfs.acme.com/test-collection/_apis/graph/users
I know its not credentials issue since I manage to make other api calls successfully.
I could not find any documentation for on-prem. Cloud version: https://learn.microsoft.com/en-us/rest/api/azure/devops/graph/users/list?view=azure-devops-rest-5.1