Could those billions be used to change all electrical generation facilities to not use fossil fuels? And then turn all public transport in the world to electric ones? And then private cars, heating, and so on?

Yes, that could be expensive, but you don't want to know how expensive will be to do nothing.

In fact, billions were already used in denialism campaigns by Shell and other companies, if they can use billions for that then well we may charge them trillions to mitigate what they put all of us into.

But no, the chosen way will be to blame others, try to reach a mythical net-zero and increase extraction of fossil fuels and pumping it into the environment while they last.