Azure Resource Graph Explorer

Find all regions where resources are located.

resources | summarize resourceCount = count() by location | project location, resourceCount

Find all regions where VNets are located.

resources | where type == 'microsoft.network/virtualnetworks' | summarize count() by location | project location

Query for all the types resources in all regions.

Resources
| summarize by type, location
| order by type asc, location asc