If your neighborhood mechanic can weld with a bottle of acetylene and a bottle of oxygen, then why can't astronauts carry oxygen in some bottles in their space craft? By the way, in 1969 they were not using pure oxygen, it was too dangerous.
What does the ozone layer have to do with it?
You are being lied to by imitators of Bert Sibrel who originated this fraud about 16 years ago for personal profit. He is merely a first class liar.
More than 400,000 people in a dozen countries were involved in the Apollo programs, including laborers, contractors, radio technicians, engineers, politicians, government workers, scientists and the astronauts themselves. It is not possible for all these people to keep a supposed fake secret for almost 50 years.
It developed over 16 years in a perfectly understandable and rational way. We first saw the tiny Soviet Sputnik 1 satellite in 1957. I personally saw the casing pass over Australia. It was followed a few years later by Yuri Gagarin and then John Glenn orbiting the Earth. For several years the Soviet Union was ahead of the Americans with the first woman in orbit and the first space suited exit from a capsule by Alexei Leonov. It was just a question of who would get to the Moon first. What we didn't know was that the chief of the Russian space program was ill and his deputy was not the best man for the job.
In 1966 or so the first globally broadcast TV show happened, featuring the Beatles among others. All made possible by satellites. New things in space were becoming almost routine.
But eventually the USA began to overtake the Soviet Union. The Mercury program orbited one man at a time, then two in the Gemini program. Then both nations managed to dock separate spacecraft together. Then the Russian heavy lift rockets failed for a couple of different reasons.
The Apollo program did all that had been done before and orbited three men. Apollo 9 did docking operations. Apollo 10 sent them to go right around the Moon and back.