I recently took the night train from Innsbruck to Hamburg in a brand new sleeper car run by ÖBB and those are a blast.

Searching for more routes I stumbled across this map and a pretty neat database of available European connections https://back-on-track.eu/night-train-list

Hope to see more connections in the coming years.

This lets me link to Seat61, who have an excellent guide on taking NightJet trains (and all other European rail travel): https://www.seat61.com/trains-and-routes/nightjet.htm