Very Cool! If this board is 96boards compliant it may be worth you reaching out to them to see if you can list it in their 96boards mezzanine section.
Thanks for the positive reply! The board is 96boards CE compatible and I will submit a pull request to 96boards/website repository. However only FPGA boards that have Global Clock capable pins that matches the Ultra96 mapping on the low-speed connector (this is not specified by 96boards) will have a good PLL input. Still it can be useful for connecting low speed TTL signals over coaxial cables I guess.
We needed clock inputs 2xSMA 1 PPS and 10 MHz 3.3V biased square wave over 50 ohm for our application. We did not find anything off the shelf so we designed a simple board with KiCAD.
We thought others might also need this. Check it out https://lightside-instruments.com/index.php/product/clockinput4ultra96/
This board is now part of the Network Programmability kit for Ultra96 project.