All objects fall at the same rate, regardless of mass. How do you “proof” it?
The astronauts did the “hammer and feather” on the Moon during the Apollo 15 mission.
Brian Cox did a “feather vs bowling ball” on Earth at NASA’s Space Power Facility.
Brainiac did a “car vs tyre”.
By the way, Galileo had only water clocks and his eyes to work with. No stop watch, no slow motion video. But he brilliantly proofed his case by rolling balls down inclines. (The dropping of balls from the tower of Pisa is fake news)