Yes, I would imagine PoW for Ethereum was millions of GPUs at least

It doesn't. A steel mill produces 200,000 tons of steel per year (at the low end) and consumes 770 Kwh of energy per ton, which works out to 0.154 Twh per year. Post-merge ethereum uses 0.0026 Twh, so about 1% the energy usage of one steel mill

Some produce up to 3,000,000 tons, so the ethereum network would consume about 0.1% as much energy as one of those

edit: Bitcoin for comparison consumes somewhere around 100 Twh, so is comparable to 1000 steel mills (which might be more than the number of actual steel mills in operation globally?)