I'm using off-the-shelf USB GPS receivers for my X8 Drone (pidrone.io); in some quick testing this morning, I'm getting somewhere between 4 and 7 satellites depending on which receiver I'm using; in contrast my DJI Mavic gets 10+. Mostly my receives are just GPS; one suppports GLONASS also, though ironically that has the worst reception.
The current set do not track a 2m square autonomous flight well - see this blog entry.
Do you have any recommendations of GPS receivers, either UART or USB connections.
P.S. I realise this is almost certainly a repeat of many similar questions, but I have these specific requirements for my Raspberry Pi X8 quad.