As a programmer with serious mobile experience I fully understand it. But it sound a bit crazy that a powerful and more superior (and open! In both hard and sometimes soft - if with an opensource OS) platform need so _emulate_ an embedded one (mobile, usually at least partially proprietary one) to provide turn-by-turn nav: what appears to be a first-order need of anyone in the modern world.
I remember the time I was heading south from Syracuse in an area notorious for state police speedtraps when I had pulled alongsides a greyhound and my son had logged into the WiFi on board the bus. The bus driver got pissed at us and got up to 95 mph to shake us. I gave up first but I figured he'd have a lot more to lose from getting a ticket than I would.
You can run OSM in navigation mode, I suppose.
However, although the devices might run on ancient stable standard, but that does not mean, that operating system is not playing silly games there. If you had an app that talked to them via serial port, you could throw it away once Microsoft introduced GNSS subsystem.