Either you have a piece/whole thing that is identified as an alien craft or you don’t.
Sightings are a different cat, especially if filmed by a reportedly reliable source, I.E. military aircraft films.
H.G. Wells “War of the Worlds” scared the crap out of many people because it sounded so real on the radio, but it wasn’t.
Even a Fox commentator today confused a fireball (meteor) with a flying saucer. There is no limit on gullibility and con-artists, or dupes and suckers.
Calling P. T. Barnum. You are back in vogue!
It comes down to the particular YOU, doesn't it? Maybe we can get Sandy Burger to go into that deep underground bunker and sneak something out without anyone noticing. We can give a tarp to thrown over something big.
I'm just observing.
But there is circumstantial evidence (which is why some in the media are willing to make a leap).
This guy claims they have not just one, but "numerous" intact craft.
His claims are based on what he has been told by military insiders in his position as representative of the National Reconnaissance Office to the Unidentified Aerial Phenomena Task Force and as co-lead for UAP analysis at the National Geospatial-Intelligence Agency (NGA) as its representative to the task force. As an aside, he helped draft the language for the National Defense Authorization Act of 2023 which included the establishment of the AARO and indemnification of government whistleblowers from their NDA's (when testifying before classified Congressional Committees on the subject of UFO's).
Here's a little more: [The] intelligence community inspector general found Grusch's “allegations that there is a [UFO crash retrieval] program [to be] urgent and credible.” (from the article above)
The problem with any proof is that it is classified for the obvious reasons.
Bottom line: Skeptics keep an open mind. A closed mind (bias) is a feature not of a skeptic but of a debunker.
Nothing wrong with being debunker, but a debunker isn't a skeptic.