Virtually any MQTT broker is Sparkplug compliant, since it's just a payload and topics definition proposal.

There's a thing called Sparkplug awareness, though, adding some requirements: https://sparkplug.eclipse.org/specification/version/3.0/documents/sparkplug-specification-3.0.0.pdf (see "12.66. Sparkplug Aware MQTT Server")

We could add this additional functions with a vmq_sparkplug plugin. Sparkplug is currently being quite actively promoted and marketed. Whether this mirrors a real industrial need is to be determined.