Yes, a brilliant move means that the engine either took to long to find it or it didn't find it at all. A brilliant move waves the game's sides heavily.
Brilliant Moves in New Game Analysis Report

https://www.chess.com/analysis/game/live/75139283201?tab=review
is the last move before checkmate considered a sacrifice?
My friend and I decided to do a game where we blunder a lot of pieces and I accidently got a brilliant.
Chess.coms analysis is proven again to be completly useless
Lxg6 is defintiv not briliant
By the definition of what we have read of how something is considered 'brilliant', perhaps it is. To me...no, but perhaps the programmers consider 1700 weak enough to merit giving it a '!!'?
There are books written on 'brilliant play' in chess...the definition varies.