The other options: Tom Hanks
The Academy, bizarrely, had been cool on Tom Hanks in recent years, ignoring his impressive work in, say, Captain Phillips. So cool that he hasn't been nominated since 2001! But the temperature turned, thanks to his performance as Fred Rogers in A Beautiful Day in the Neighborhood, which is, yes, very much a supporting role. (Matthew Rhys' journalist is the lead.)
Hopkins is surprisingly funny as Pope Benedict XVI, one of the two popes in The Two Popes.
Frankly, as evidenced by my success at predicting this category, the other contenders were long shots. I was pulling for Song Kang Ho to make it in for Parasite, but that hope was far fetched. Just Mercy has largely flown under the radar, but Jamie Foxx ended up with a SAG nomination.