Almost everything in James Bond films can be made work or already exists in a similar form but NOT the infamous tiny twinset used by Sean Connery in ‘Thunderball’.
The 7.5 gram sparklet cylinders have an internal volume of 10 ml filled to 5.7 bar with liquid carbon dioxide which gives a total volume of about 6 litres of gas. The 16 gram cylinders used in DSMBs (Delayed Surface Marker Buoys) would obviously give a bit more.
The burst pressure of a sparklet container is only 50 bar. But as air would not be liquefied you would only get about 0.25 litre from the twin set at 5.7 bar. Assuming the cylinders could be redesigned for say 200 bar then this twinset would give 4 litres. That’s just one breath at the surface!
So Bond’s escapades underwater using this tiny mouthpiece twinset was pure movie magic. It could never have worked in real life.