GPS support is enabled in all STM32 devices.
Only the MK22 (GD-77S, DM-1801) has special build for this (as none of them has embedded GPS module, and memory is really limited).
There is a dedicated thread about fitting/replacing module. Basically, the module has to spit NMEA strings at 9600 bauds, TTL level (3.3V).
Cheers.
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Daniel