Within the far reaches of my imagination, I have developed a portable oxygen device that is powered by a few twigs of bioengineered super Elodea. You know that plant that you grow in your fish tank that produces oxygen for your fish.
Picture this!!! Instead of oxygen flowing from both prongs, we have oxygen entering from the right prong and carbon dioxide leaving through the left prong. The oxygen is being produced by the super Elodea which has been biologically engineered to produce 100 times more oxygen than the garden variety that you have in your fish tank. The carbon dioxide is going to the container in which the Elodea resides.
Remember that this is super Elodea, so one twig should do, and the amount of water needed would be small so the unit would not weigh much. It would require a small battery to provide power for a small led light so that the Elodea would continue to produce oxygen, or better yet the Elodea would be engineered to not need light.
I hope that you have had fun because I have. Now and then we need to lighten our burden.