I have iGO Primo installed in the NAND Flash on a PC*Miler 430, with maps on a 4 gig SD.

Getting the maps working was easy, just change 0 to 1 in has_secondary_root with the maps in igo\content\map on the SD

What is proving to be a problem is how the GPS receiver is connected in this device. The port was set to 2, didn't work. All the other WinCE 5 GPS receivers I have work with port 2, 57600 baud. I tried changing port to 1 but still nothing. The GPS menu shows it receiving data from multiple satellites but doesn't tell me tech details of the port and baud rate.

Is there a hardware info app that will work on a stripped down WinCE install?

[interface]
show_exit=1
resolution_dir="480_272"
vga=0

[rawdisplay]
highres=0
screen_x=480
screen_y=272
stretch=1

[gps]
port=1
baud=57600

[interface]
extra_settings=1

[power]
skip_suspend_process=1
skip_resume_process=1
skip_suspend_process_all=1
skip_resume_process_all=1

[warning]
speedcam_warning="1"

[sound]
ding=1
sound_q_length=200
queue_length=200
mute_os_key=1
pause_mp3_sooner=1

[tts]
tts_buffer=131072
announce_exit_directions=1
tts_logics=3
priority="HIGH"
always_say_road_names=1
announce_street_name=1
skip_exit_numbers=0

[navigation]
sim_speed_factor=3.0

[folders]
has_secondary_root=1

[gps]
port="auto"
baud="auto"

Try those entries in sys.txt and see if it works.
If it still doesn't work try adding source="nmea" under the baud line.
Or you can just try different port numbers instead of 2, 7 is a common one on older devices, my CE5 Navig8r's use 7 and a baud of I think 38400.

Did some more digging. GPS Menu Pez included an information tool which revealed this is a Mesada device. So I went looking for serial port information for Mesada and found [Please Register or Login to download file]

There's a text file there with the very last line
Navigation interface type: UART-COM2 4800bps

I changed the settings for the port to those and now iGO sees the receiver and gets data (when outdoors). Now, what about increasing the port speed? I got Cregedit 0.0.5.2, which was very difficult to find a site that actually had it without expecting money, signing up, allowing it to spam me with notifications, or only had a link to the dead original download site.

Port speed might be limited by the hardware or perhaps the UART protocol.
I guess you know the risks associated with messing with windows registries.
Good luck!