Answer: We have four variants of HL6528 as following:
Without GNSS :
1.8v HL6528 (GX)
2.8v HL6528-2.8V (GW)
With GNSS :
1.8v HL6528-G (GZ)
2.8v HL6528-G2.8V (GY)
We can know the HW variant by sending AT+KGSN=3, for example:
AT+KGSN=3
+KGSN: GW338100120302 ----Here GW means the HW variant is a HL6528-2.8v without GNSS
OK