At the end of this video, he compares the Raspberry PI 400 to the ZX81. Seems like a fair comparison, although the Timex Sinclair 2068, which is a computer that Ioved, might be a closer comparison.
I couldn't find a CPU benchmark, but I have a refurbished laptop that I got for $80 that probably outperforms it. Still, this seems like much computer for the money. I wonder if one could get a used PC for $100?