How are you getting back to Munich after the game? Trains won't be running I don't think. I know Goughy's coaches are over there running a Munich > Salzburg coach so may be a possibility. Our flight back to Brum from Munich doesnt leave until 17:20 on Thursday so will have some time to get the train over although I read no need to go back into Munich HBf, can change on way and head to airport.
Google Gemini tells me that trains run through the night:
The 03:39 AM train from Salzburg is arguably the sweet spot for your strategy:
00:00 – 03:00 AM: Celebrate the match, experience the late-night fan atmosphere in Salzburg's city centre, and slowly wander back to Salzburg Hauptbahnhof.
03:39 AM: Board the direct EuroCity/EuroNight train back to Germany.
05:28 AM: Roll into München Ost.
05:35 AM: Hop straight onto the S8 S-Bahn heading to the airport.
06:05 AM: Arrive at Munich Airport terminal.
I hope that this isn't one of those cases where AI got it wrong. Further investigation and confirmation is needed, methinks.