Instead, they present a custom USB vendor/device ID that the kernel doesn’t immediately recognize as a serial device.
Without the driver:
With mstar_usb_serial properly bound:
$ lsusb Bus 001 Device 004: ID 1a86:7523 QinHeng Electronics HL-340 USB-Serial adapter (Kernel might treat it as CH341 serial, which often works partially but not perfectly for GPS.)
Check if it’s loaded:
