I tried some of SiFive's evaluation cores. They limit you quite a bit unless you pay. Furthermore, many of the FPGAs worth their salt were quite expensive. The K210 in the MaixBit form is only $20, and it comes with a camera and LCD. For hobbyists, I think it's a good compromise.

I looked at the Xilinx FPGAs--the ones SiFive recommends, but they're quite pricey.

Which FPGAs had you had luck with?

I haven't used them myself, but these boards look awesome, and they are supported by an end-to-end open source toolchain:

1. https://www.crowdsupply.com/1bitsquared/icebreaker-fpga 2. https://www.crowdsupply.com/radiona/ulx3s 3. https://groupgets.com/campaigns/710-orangecrab

I was looking at getting this Maixduino kit since it appears to be the cheapest solution that satisfies my constraints (RISCV core + WiFi):

https://www.seeedstudio.com/Sipeed-Maixduino-Kit-for-RISC-V-...

I'm not sure what's the status of programming these from Rust. I suppose that you will probably need to build your own toolchain that links the Seeedstudio libraries.

RISC-V has their own supported toolchain. You can get it here: https://github.com/riscv/riscv-gnu-toolchain.git

With Rust, you can do what I did with my OS. It can compile out of the box. The kendryte has a "BSP" (base support package) that is essentially a minimal OS, but it is written in C.

Yeah, I was thinking more about what to do with the OS afterwards. That board has lots of things on it, including wifi, so I'll probably would like to use some of that.

It would be unfortunate to have to re-implement the wifi driver in Rust, but I suppose I'll just have to link parts of the C toolchain instead, creating Rust wrappers, etc.

Well, FPGA are more flexible but cost more than a cheap microcontroller that is true. There are way too many good options, but to pick one with a fantastic community: ULX3S