Excellent callout. Might be a component of Starshield. Hard to say until the RF is active in the wild or FCC filings are public (is it possible SpaceX is filing in Tonga to sidestep FCC public filings on the tech?). Would be wild if this system will be able to provide global airspace radar surveillance to the US DoD with high precision.
https://www.space.com/spacex-starshield-satellite-internet-m...
https://www.spacex.com/starshield/