Not all experimental proof comes from NASA. There's an extensive list on Wikipedia.
https://en.wikipedia.org/wiki/Third-party_evidence_for_Apollo_Moon_landings
When I visited the Kennedy Space Center, I had an eerie sensation that the moon in particular, and space in general had been privatized. Much like the Portuguese and the Spanish who divided the world in two equal parts in 1494 with the Treaty of Tordesillas to the exclusion of all other European nations for colonizing the non Christian lands. Although ignored later by the other nations, scars of this treaty can be seen in the maps of the world.
Given this precedent, it should be of no surprise if one day it come to light that those "independent" third parties had to sign an NDA.
Notwithstanding, the junk found on the moon doesn't mean someone landed there. In 1972, Lou Reed had a premonition:
Satellite's gone way up to Mars
Soon it'll be filled with parkin' cars
Up to now seven rovers have been dispatched there, and not a single terrestrial microbe had that chance.
Much of the evidence for the fact of the Moon Landings is from 1969 & the early '70s, when nobody would have known what an "NDA" was.
In any case, they are a poor protection, as a Congressional Investigation or a Royal Commission can turn your NDA into confetti any time they want to!
The "junk" had to get to the Moon somehow, which means transporting quite large pieces of equipment there, positioning them quite accurately, somehow make astronaut footprints, somehow drive the buggies around, all without leaving any evidence of artifice.
This would be hard to nearly impossible to do with today's technology, let alone that available in 1969.
NASA didn't know that they had such a long "breathing space" as it transpired they did.
For all they knew, a Soviet landing or even a manned orbiting mission could have "blown everything", so they somehow would have had to develop all this advanced automatic transport & equipment handling capability before the deadline set by JFK, whilst running a "fake" parallel Apollo program.
They then, in a huge rush, had to use it to plant Apollo 11 evidence, & continue to do the same thing in secret for all the other missions.
This is when the technology "wasn't good enough for a manned mission", according to
your unsupported statement!