Provided the gpx file has waypoints, Pathfinder mode will read the file with no issues. It doesn’t recognise tracks or routes though. Breadcrumb trails of waypoints are fine.
As for the aerpro adaptor I suspect it won’t work, but happy to be proven wrong. Reading the user manual it appears to need a usb connection with the head unit and also a Bluetooth connection to your iPhone. The grenadier is wireless CarPlay only. No mention of Android auto in the manual.
Unfortunately Hema doesn’t support CarPlay or android auto. Maybe some day…. but it would undermine their hardware based mapping products. They just killed their Explorer app and the 4wd app hasn’t been updated in 2 years on the apple App Store.
The only CarPlay compatible navigation app I’ve found which allows me to load my own maps and imagery is OSMAnd maps, but it’s not a simple process to get them into a suitable format that OSMMaps can read.
Cheers
Steve