If I absolutely had to have a dedicated device that some scrote might want to swap for a brick, it would be a TomTom no question. My previous car had Garmin satnav integrated in the head unit, it was gash (just like every other OEM satnav I’ve encountered).
If I absolutely had to have a dedicated offline phone app for routing, it would be CoPilot. But, why would I want to?
Android Auto / Google Maps just works, I’ve been using it for years ahead of integrated systems costing four figures. I’ve had dalliances with Waze but keep coming back to Google Maps. It’s not perfect, it sometimes wants to send me somewhere random to shave six seconds off my journey, but it is hands down the least imperfect solution I’ve ever used.
Does your van not have a speedometer? Genuinely, I’m not really understanding this use case. Put your phone/tablet where you’d put the Garmin, look at your dashboard to work out how fast you’re going.