Lets you use a $10 ESP-Prog programmer as the equivalent of an Altera USB Blaster.
The FT2232HL on the ESP-Prog supports JTAG/MPSSE, which means you can use it to flash an FPGA using openFPGALoader.
This board can be ordered assembled from JLCPCB using the gerbers and BOM included in the release/ directory. Or you can hand solder it, obviously.
It works. Tested with Waveshare CoreEP4CE6.
openFPGALoader -c ft2232 --fpga-part ep4ce622 -f [binary].rbf