PicoRio Linux RISC-V SBC is an open-source alternative to Raspberry Pi board
Promising hardware, though this isn't looking like comparable hardware even to the Raspberry Pi Zero. Only has a quad-core 64-bit RISC-V (RV64GC) processor at 500+ MHz.  RAM size not specified. If it was priced in the $5-15 range it would be more or less practical, but higher than that I'd be buying it solely for the architecture novelty.