I suppose the Leo Bodnar Mini Precision GPS Reference runs on USB-power, either from a Computer or a USB-Charger. The larger one has a DC socket. Look at the pictures :
For the larger one ( not Mini ) the site states: "It does not need any drivers installed or even USB connection. You can use external 12V power supply without USB attached."
There you have it. Once you have a stable 10MHz clock, you may also derive the 25MHz for your LNB from it.
Take a look here: https://wp.project-launch.net/
It shows what you can do if you want to build it yourself. F1CJN took it a bit further by using a OCXO instead of a TCXO, DL4ZAO and DL7UKM made a nice PCB with features like Measurement of Control-Voltage, I did some cosmetics and incorporated a temperature sensor and a bit of code to handle a Si5351 for 25MHz output and some features for the display - like show time with leading zeros etc -that initially weren't there.
There will be a virtual lecture on the "UKW-TAGUNG" in Weinheim, which will take place online. Find info here:
There is a Translator-applet in the upper right corner.