This newish u-blox device looks useful. It is designed to lock an OCXO to GPS directly without the usual PLL components and requirement for a 10kHz output.
https://www.u-blox.com/sites/default/files/products/documents/LEA-M8F_DataSheet_(UBX-14001772).pdf
Are you aware of any OEM prodcing mini pcie boards with this device? Trying to put together a Linux NTP server using this as time source