Some hams want to work with FPGAs to generate high speed PN sequences in the GHz range. LFSR designs are about as simple as you can get in an FPGA. The only trick is getting the resulting signal out of the FPGA. Rather than outputting a parallel word at some 100's of MHz into a shift register clocked in the GHz range, it seems easier to use a SERDES to shift it out directly from the FPGA.
But not all FPGAs have SERDES. Which are the lowest cost devices and the easiest to use? By "easiest" I mean board level with a built in programming interface so they just connect a USB cable and maybe power supply, no dongle needed.
All the FPGAs I've worked with lately (by that I mean over the last 10 years) didn't include a SERDES.