Claire Wolf's PicoRV32 seems to get a lot of "simple and synthesizable RISC-V design to run on a cheap FPGA" use, although that's more typically for much cheaper FPGA's than an Artix A7, like an iCE40. SeRV is even cheaper and simpler but much slower. Graeme Smecher’s RVC-first "Minimax" is almost as simple as SeRV but not nearly as slow.

I haven't tried any of them, though, so take this with a Himalayan salt lamp.