Just to add a little more information regarding the absence of Peterka and Reichel. I watched an interview with the coach Tobias Abstreiter who explained it like this:
Lukas Reichel chose to opt out of the WJC because the Hawks told him that there may be a chance for him to play in the NHL soon, possibly even during the time of the tournament, and he did not want to risk not being available should the chance to play in the NHL present itself. But the Hawks had given him the green light to play at the WJC if he wanted to.
With Peterka things were slightly different. He wanted to play, if the Sabres allowed it, but the Sabres said no. Mostly because they do not want to lose a player given the uncertainties with COVID. If they were to lose a number of players to COVID protocol, they want all their best options available in the AHL for eventual call ups.
Can't really blame either player or either team here.
Another interesting tidbit from the interview was, at least for me, that Niklas Lunemann was somebody the coach did not really have on his radar for this tournament before he became a late addition to the roster for the tournament in Norway a few weeks ago.
The interview was obviously in German, but if anybody is interested it is on youtube: