Shocking!
For clarity and to try to pull some threads together.
This is not gaseous CO2 from a cylinder. This is solid dry ice which turns to gas (sublimes) at known rates depending on the packaging. It is already in packaging when it arrives at the ac. The ability of the ac air systems to change the air is known. All of this generates limits on the amount that can be carried. We have been doing this for years, it is known stuff and although it may sound new and scary it actually isn’t.
We’ve started moving vaccine around the world in mixed freight.
FWIW my 757 with 2 crew has sufficient O2 for 3 hours at 100% at 25000’.
I’ve deliberately confined myself to freight only ops as it’s 18+ years since I operated a pax ac.
Hope all of this helps, I’m not sure there’s much else to say on the matter. I hope that @OPENDOOR feels that questions have been answered.