@xymox Welcome!
I don’t believe NTPD supports 5Hz PPS signaling. Others have used 5Hz PPS with Chrony/GPSD with debatable benefit. Ordered me a new GPS - #8 by Bas
I am able to achieve approximately +/- 1.5 usec offset with the 1Hz PPS signal connected to my pfSense firewall. I increased the baud rate to 38400 to reduce fudge time2. 5Hz/10Hz PPS doesn’t seem to be worth the additional time and expense in my application.