I'm very sure that Man United is possible to beat Lyon. Man United performed well in UEL, they have enough players to play against Lyon. It is true that there are some injured players, but I think it won't be a problem for Amorim. Lyon is also not a very big team in Ligue 1, Man United has enough quality players to eliminate Lyon. Even if it will be a tough match, Amorim should have the way to deal with Lyon tactics. For the international match, Amorim looks better during he is managing Man United. So, I'm confident about Man United defeating Lyon.
If it is seasons ago when Manchester United played better and had experienced coach like Jose Mourinho, I can agree with your thinking. Now in 2024 - 2025 season, with big crisis in Manchester United and with a young head coach like Amorim as well as his bad management and results so far in the club, I am very pessimistic about Manchester United chance in quarter final matches against Lyon.
Lyon are no longer a dominating club in Ligue 1 but Manchester United have their own quality decline too and their declines make this match more balancing, then very unpredictable. Amorim can use tactics that he sees fit but Manchester United players have very inconsistent performances in this season. With only two matches in quarter final, if they show off inconsistency and poor performances, they will be out of Europa League and Lyon will move next.