They present you with a legal form you are to sign stating your purpose of stay. This is what the Marriott did to me this past weekend.

They will also take interest in any supporting documents (like an essential worker letter).

Be aware that they are doing this for legally protecting themselves. From my experience, the hotels are nearly clueless on the rules (aside from the number of days of quarantine) and I had to give them the notice published by the Bavarian government to help them out. It's the first official thing they've seen.

Note that just because I said they are clueless as to the details, this does not mean they are failing to take matters seriously regarding sanitation & social distancing.

Immigration, customs are giving more scrutiny, as they are actively trying to weed out tourists. However, they have no info as to my responsibilities once I arrive.

One issue I have had to deal with was how to be tested after 5 days. There's plenty of testing opportunities in Munich, but everything is set up for German citizens only. If you are not a citizen, apparently you cannot be tested. The facilities told me to contact the local health authority, and when I did, they gave me locations for citizens to be tested and told me I am responsible for filling in the registration form required for people flying in from overseas. Great info, but useless.

It appears the only way I have found to be tested is at the airport at the Test&Fly center. There are two testing centers there - one is for citizens, the other Test&Fly one is a paid service. Bonus is you get your results in a few hours if you test early in the day.

I have a couple days left of quarantine before going there.