I'm pretty sure you're wrong here, and Greta doesn't fly, but if you insist, can you share your sources?
https://en.wikipedia.org/wiki/Transatlantic_Voyages_of_Greta...
The word "emergency" occurs once, in phrase "Thunberg does not fly except for emergency cases.(4)" . The link (4) leads to https://time.com/5663534/greta-thunberg-arrives-sail-atlanti... "Climate Activist Greta Thunberg, 16, Arrives in New York After Sailing Across the Atlantic" . I didn't read the whole article, are you saying that article says Thunberg flies?
So I'm still not sure where's the information supporting "Not just that she flies around the world instead of doing zooms." coming from.
"Significant carbon footprint" asks for, significant compared to what? Maybe Greta leaves bigger footprint than the lowest, say, 10% of the Earth population, who don't really have access to modern technologies with that significant footprint. But she surely tries quite a lot given the circumstances where she is, and encourages us to follow. So I'm skeptical about accusations towards her without enough evidence.
https://www.iea.org/commentaries/the-world-s-top-1-of-emitte...
She is most likely in the 90% percentile not the 10% percentile. Which is my point. We shouldn't look to people with huge carbon footprints as role models. Al Gore for example has multiple homes. He is easily in the top 5% of carbon footprints in the world.
If the most alarmist and upset climate activists cannot get their carbon footprint down below the average human, then it is pointless to try. The only fix for this problem is technological acceleration toward clean energy, even if getting there causes short term emissions to increase.