> carbon-free energy on every grid where they operate also sounds like a significantly more ambitious goal than net-zero across the company, because it means actual reduction in emission

Not necessarily. In the UK the market for zero-emission electricity is separated from the actual electricity itself. So you basically sell the "greenness" of the electricity separately from the electricity itself. Customers who want green electricity buy the electricity, and buy some "greenness" (called a REGO).

It does make sense, and a lot of people claim it's some kind of scam when it really isn't... But it does make the relationship between the consumption and production of green energy more complex.

For example, suppose 10% of power comes from green energy, but only 5% of people care about it remotely. The market value of a REGO is basically zero. Even if the number of people who care about green energy doubles to 10%, there's still perfect supply so the market value is still zero and it won't have any effect on green energy production. That isn't quite the case but it doesn't seem far off - I couldn't find up-to-date numbers but it seems like the market price of REGOs is on the order of £5-15/MWh, which is very low. Probably because the UK's energy mix is actually very green these days.

No idea how common this system is in other countries.

"24/7 carbon-free energy" is actually a much stronger goal, because (for example) it's physically impossible to buy solar/wind energy on a calm night, so they would need to pay more for an alternative like batteries or nuclear.