How can I use custom attribute for the bar label for data resulting from Tempo query?

I’m using Grafana Tempo+Prometheus.

I’m attempting to display a comparison between a discreet set of span data via Tempo query. The queries use attributes on spans to get a complementary set of spans (~50) a day apart. I’m wanting to show the duration of these, with each bar’s label coming from an attribute/tag.

How can I set the bar label to come from a Tempo attribute/tag?