Sorry it's been a while. Yes flying to mexico and then to the US after 14+1 day worked. You do not have to quarantine in Mexico and i did not have to quarantine in the US either. Going back to germany as long as you have a permanent residency or german passport is not an issue. However you will have to quarantine 14 days after re-entry.
Unfortunately this will get a lot more difficult with the new US administration. Not only will they keep the same (kinda senseless) ban in place, you will also have to quarantine when entering the US from any international travel. Meaning you need 4!! Weeks. 2 outside the shengen area, and another two after you finally get to the US. And of course another 2 weeks of quarantine when you get back to germany.
For people like me that have to work. Pretty much impossible. My hope was for the bans to be lifted sooner or later but the Mutations going around kinda make me question if we will travel at all again. Sad. Tired and desperate of the whole situation. Like a lot of us here