The cars are not the sustainability issue. If every modern car was as efficient as F1 cars then we would be in a much better spot regarding climate change. The issue is with the massive transportation effort involving planes, trucks, and ships required to transport materials between the races.
It's about the perception, not facts. The general public does not know about transportation in F1. They know that F1 cars still make wroom when they sit in the growing number of VW id.3 cars that are making silent SciFi sounds.
They are very efficient yes. But at the same time they aren't very reliable. If everyone was running an F1 style engine and would have to replace loads of parts constantly we would be in a much worse spot.
If it was such a good system don't you think we would already have such engines in regular cars ? There's a reason why we don't. Because these systems only work when that engine has to only run for little time in very confined scenarios.
They aren't very reliable because they run at the ragged limits. It is a competition, after all. Motorsport has always been like that, nothing to do with current PU tech.
The reason we don't use them in regular cars is because it's expensive to make, and combustion engines are being phased out anyway.
No, running engines at the limits makes things less efficient, which is why on fuel-limited tracks you see a lot of lift and coast and turning down engine modes when that was a thing.
The efficiency comes from having two different complex energy recovery systems, which is what makes them expensive to transfer to the road.
Still, you'd see more real world applications if countries' carbon regulations were tighter.