The PPS can be good (pi kernel support is stable), but one needs to be careful as some modules PPS signal has a great deal of instability.
Some U-Blox modules support the additional ground based navigation signal and cellular beacons. This is recommended in addition to the 3 satellite networks classes, but note some modules will not work with some antennas (get the unified hardware with built in antenna/lna if unsure about RF notes).
If you have good sky visibility, then I don't need an antenna. Though this often tends to mean putting a Pi outside. I'm also using just the first Antenna I find actually.
I have good results with cheap ublox 6m's and 7m's from aliexpress. For some reason the 8m's I got were poor in sensitivity.
Adafruit ones also work great, but are a lot mor expensive, I do have several though.
PPS is criticial to proper timing. However... I was using the time synched systems for sound localization. But as they only cost around 7 euros on aliexpress, why not.
Some U-Blox modules support the additional ground based navigation signal and cellular beacons. This is recommended in addition to the 3 satellite networks classes, but note some modules will not work with some antennas (get the unified hardware with built in antenna/lna if unsure about RF notes).
Best regards, =)