Jaeger can use multiple backends for storage, including Tempo, so it's not an either/or situation.
I'm fairly sure there was an official Grafana-provided Jaeger gRPC plugin for Tempo, but can't easily find it, only this one: https://github.com/flitnetics/jaeger-tempo
I'm fairly sure there was an official Grafana-provided Jaeger gRPC plugin for Tempo, but can't easily find it, only this one: https://github.com/flitnetics/jaeger-tempo