It's just a friendly game and against a weak American team but still Bayern's first match was glamorous. Especially new transfers showed their skills and scored some goals. That gives us a sneak peak of how new season would be without Lewandowski. Mane started with a penalty in the beginning of first half and De Ligt started second half with a goal. Zirkzee had a great year in Anderlecht and in U21 championship, now he wants the jersey here. Mane - Gnabry duo looked like they were going to do well together. This 4-4-2 tactic work well against lower teams. The real test will be Manchester City friendly game three days later. We might see another tactic there.
I watched the highlights of this match and i have to agree that Bayern looked pretty good in that match. The new players Mane, De Ligt and Gravenberch all showed a good performance in this match which is nice to see as it looks like if they are already part of the team. I think especially Gravenberch had some really good situations. Of course as you already said this was just a friendly match against a second tier team and Bayern Munich basically switched out the whole team in the second half so the result is really not meaning that much.
ManCity will be a harder game but it is also just a friendly game where both coaches will try out as many players as possible. The real test come will come with the first real match.