Is your proposal related to a problem?

I can't use sort_by_label promql experimental function in thanos-query to sort results by a label, e.g. "environment", where the values are like "dev", "qa", "uat".

This is needed to display results in Grafana Stat panel in a logical ordering.

Describe the solution you'd like

I would like to be able to provide a feature flag argument to the thanos docker image which enables promql experimental functions (sort_by_label, sort_by_label_desc, ...).

Describe alternatives you've considered

I can't add my prometheus instance as a separate Grafana Datasource, or an endpoint in thanos-query, because all of my long-term metrics are coming from S3 via thanos-store.

Additional context

Please see Issue #4022 or PR #4786 for an example of adding feature flag support.