Have you tried it out in an FPGA?

Not yet! But that's our next step.

tang nano 20k. You can't find any cheaper fpga board than this.

You can apparently use the open source yosys/nxtpnr tools with the tang nano 9k, but, unless something has changed recently, nxtpnr doesn't work with the 20K yet. However, I found the Gowin tools to work reasonably well (and definitely way less bloated than the Xilinx & Altera tools.)

At a higher price point but with more capability, Digilent has a one-week 20% sale on their FPGA boards this week. Some good options (Artix 7 and Spartan 7) within spitting distance of $100.

From what it looks like (Xilinx parts primarily) if I bought one of these boards I'd be stuck using either Altera or Xilinx tools. I think some spartan 7s work with yosys/nxtpnr, but not sure how well.

Yep. The Xilinx tools are very, very good; but they're definitely proprietary.

> The Xilinx tools are very, very good

Ummm... no, that has not been my experience at all. I'd replace 'good' with 'buggy' in that sentence. And also very, very bloated - like 90GB bloated. I've had good experiences using yosys/nxtpnr/SymbiFlow, but that's kind of limited to the Lattice ICE40, ECP5 families and Quicklogic.