scanner and black box to generate an Ethernet signal for feeding to any suitable software, showing the radar display on a computer.
Nobeltec sells this Koden system integrated with their navigation software. (Other do too)
Radar display can overlay the chart, or can be separate if you have enough screen space to see both. Two monitors can be set up on a PC

Seems like a workable system, but needs more know-how by user than Nobeltec's Trident would.