Could you point me to any UFO wistleblower from govenment, military, science, etc. areas that revealed exact technical details about UFO. I mean really technical - not somehing like "it could hover silently!" or "It could turn at 90° at high speed!" or senseless drawings or descriptions of exterior or interior. Something like exact weight, power source output in Watts, maximum thrust in kN, something like "Power source connected to the engine with a cable/pipe/whatever with diameter/cross-section of ... <- exact value"? Anything like that?
First thing that engineer, scientist, military will do with unknown technology is to measure it. And it is not about dimentions, it is about all possible parameters. Also he definitely will try to find and write out distinct parts interconnections and think out a way to categorise different distinct parts, even if he have no clue what it is and how it works. And that are the things that any real whistleblower from aforementioned institutions will wistleblow. They just can't be unaware of that things if they really tried to use, work on, reverse engineer or study that UFOs.
What I find very suspisious, apart of complete absense of known technologies that appeared from nowhere without any traces of preceding technologies, is that there are no any technical details about UFOs governments presumably possess from any known to me wistleblower.
You don't need to be convinced or not. Rare things need faith or believe in our life. Technical questions definitely don't.
You either know such things, either do not know. That's simple.
For now, we just don't know, have aliens visited Earth in their machines or not. Not enough information.