The only knowledge you have of the lightning network is a YouTube video from 3 years ago posted on a subreddit with a financial interest in badmouthing BTC?
I'm not really sure if this is the proof I'm looking for.
The author of the video was explaining how the LN works and it seems to be an exponential routing calculation problem ( similar to traveling salesman )
So while it could work for 75 k channels, it's not going to work for 1 million.
If the explanation of that video is correct (since you didn't disagree that), then how many channels it has now is irrelevant from my POV.
Most transactions settle in two seconds or less for a fraction of a cent in fees.