[duskwuff]

> OTOH, if you go for a lattice ICE40 based board, you can use a fully open source toolchain.

But you won't be able to synthesize a RISC-V CPU. The iCE40 series consists of relatively small parts.

[grahamedgecombe]

> But you won't be able to synthesize a RISC-V CPU. The iCE40 series consists of relatively small parts.

You can fit picorv32 on an iCE40-HX8K, although admittedly you'll only get an RV32IMC core with just the user ISA.