This is an interesting FPGA project: http://www.electronics-lab.com/ultraminer-fpga-affordable-16-nm-xilinx-fpga-dev-board-crypto-mining/
It’s 100% dedicated to mining. No GPIOs (that I can see), no external interfaces other than a (relatively) low-speed USB (probably 2.0) port.
I’m not planning on getting into crypto mining, but the board might be an inexpensive interesting to prototype larger hardware designs and then move to a board with I/O later.