Yes, you can use the german rail pass in germany and in ICE trains to Brussel and Liege, trains to Salzburg and direct Eurocity from Munich to Kufstein, Wörgl, Jenbach, Innsbruck, Bolzano/Bozen, Trento, Rovereto, Verona, Bologna, Vicenza, Padova, Venezia and Rimini(in summer).

Sure about Rimini? It's not mentioned on the German rail pass page.

NOte!! THis is quite important for this!

There is a 1 country INterrail pass DE=Germany = does NOT allow trips out of DE

and ONLY for NON-EUropeans!! there is the German Rail Pass (hence NOT for sale via this site!!) that does indeed allow also some sectors run by DB-ICE trains directly to/fro DE=Germany. It also includes a few touristy buslines inside DE.

Use google to find out more and where to buy!

What is your source for this statement? This page says differently:

https://www.interrail.eu/en/interrail-passes/german-rail-pass

It seems to me that the one country pass for Germany (Interrail and Eurail) and German Rail Pass have been merged into one.

In my understanding the both one Country offers of Eurail & Interrail are now the German RailPass offer and yes you can use the German Railpass all the way to Innsbruck (please note the German Railpass is only valid in the Eurocity trains from Munich to Innsbruck and Italy not on the regional trains.)
@Nanja  Maybe it would be possible to add the Regionaltrains & the Nighthet on that route too.

Thanks for the suggestion, Seewulf. I have passed it on the the product team to check possibilities. Cheers, 

Hi @seewulf, the Pass is a DB product- in exception to our other Passes. Since nightjets are run by OBB, we can't add them. In regards to regional trains, could you specify which ones you are referring to? 
 

OK. The Eurocity´s from Munich to Italy are a Joint Venture of OBB&DB and because of that i assumed that even the Nightjet on the route could be covered Hamburg - Innsbruck with Nightjet (and connect further with the Eurocity to Italy )

You said that the Pass is a product of DB and as Nightjet are operated by ÖBB it´s not valid on them. Does this mean i couldn´t use the Nightjets of ÖBB within Germany with a German Railpass? because there is no warning on the information pages about that.
I assumed as ÖBB is listed on the list of "Die Beförder" Int. Passofers that even covers Nightjet with a German Railpass.
Popular domestic Nightjet Routes in Germany
Hamburg/Cologne/Düsseldorf - Munich
or Hamburg/Berlin - Freiburg/Basel Badischer Bahnhof.



From Munich you can catch 2 Regionaltrainsroutes First is from Munich to Kufstein (Private operator but Railpass is accepted) from Kufstein it would be a Regionaltrain of OBB (Austrian Rail) to Innsbruck :)

the second (more scenic route) are direct regionaltrains of DB/OBB via Garmisch Patenkirchen - Mittenwald (here is the border and the change of responsibility from DB to OBB ) - Innsbruck
On the same route Munich - Garmisch Patenkirchen - Innsbruck operate even few ICE´s even with the change of responsibility at Mittenwald ;)
 

In a nutshell,

For the nightjet question:

• Passholders cannot travel on a nightjet with a GRP
• Passholders can travel on a DB IC train/ coach with a GRP

For the regional train question:

• This route will not be included in the pass. The only one included in the pass is documented in the page 3 of this document in orange: https://assets.static-bahn.de/dam/jcr:004f4965-b323-4852-aee6-3fa77fba32ec/German_Rail_Pass_2022.pdf . The only direct train our product specialist can see between Mittenwald - Innsbruck is operated by Österreichische Bundesbahnen which is not included in the GRP (https://assets.static-bahn.de/dam/jcr:18054737-a4f9-4194-8de3-a2446383e3f1/230477-308423.pdf)

I trust this answers your questions.

It's probably a good idea to mention this somewhere on the GRP pages. Otherwise this could lead to unpleasant surprises.

the EC to Italy is also operated by ÖBB in Austria, so that doesn't really sound convincing. But of course you need to draw the line somewhere.

It is listed in the Rail Network Guide in the app:
 

I will send a request to have it added to the GRP page. 

Update: It has also been added to the GRP page.