Hi I don't think what you are asking for may exist, in a single guide, but essentially it doesn't matter as from what I've seen the PiHut website links to the HAT configuration guide that leaves you with a working GPSD configuration.
Once you can confirm your GPS data is being received, it's a fairly standard NTP configuration there after to create a NTP server which will provide you with your PPS disciplined time source to output to your display ....
So in essence it's you combining probably 3 distinct guides - there's lots of guides on the net covering both the 1st and 2nd parts - the missing 3rd will just be you taking a time data string and either displaying it or loading year,month,day,hour,min,sec variables and constantly refreshing those on your display.
I'm not saying the above may appear simple or trivial to you initially, but it's not really all that hard either, after you've started playing around with the hardware, completing each part at a time - the fun is in the doing and learning.
I haven't used that exact HAT but the Uputronics HAT (Pi4) size is roughly the same setup to end up with a PPS disciplined NTP server.
So in summary, it's a combination of
1 Pi + GPSD config.
2 NTP server config.
3 Display output config.
i.e potentially easier to locate separate guides - potentially most of 1 is supplied by PiHut so you're already a third of the way home.....
"Never get out of the boat." Absolutely goddamn right!
Unless you were goin' all the way...