I hope too that most developers already know that they need to use real-time schedulers for real-time work.

But I'm not sure that you understood to the end the problem and solution.

chrt --rr 99 ./client

It's only the test machine to make sure that de0_nano_fpga part work correctly. Linux on de0_nano_fpga, of cause, run with real-time features. The times (Min: 0.74ms) are for Linux with real-time schedulers.