Appstream2.0 - Cost Explorer Tag filter

You mentioned you have 2 TAGs in 2 different regions. To be able to see the data corresponding to the tags to differentiate your resources, I would suggest that in cost explorer you filter on "regions" to choose the desired region(s) and once the filter is active; group by on the tag. Please note that at a point in time, you can group by only one tag. You can use a combination of filters and group by to get data corresponding to a specific region and tag.

Filtering Data: https://docs.aws.amazon.com/cost-management/latest/userguide/ce-filtering.html Grouping Data: https://docs.aws.amazon.com/cost-management/latest/userguide/ce-modify.html#ce-group

I would recommend to start with Cost Optimization best practice documented here https://docs.aws.amazon.com/whitepapers/latest/best-practices-for-deploying-amazon-appstream-2/cost-optimization.html. Also have you used Cost Optimizer for Amazon AppStream 2.0? https://github.com/aws-samples/cost-optimizer-for-amazon-appstream2