As a French living in Germany, I often take the train to visit some friends/family. I would say it's working well from Frankfurt to Lyon or Frankfurt to Paris and not too expensive if you have a Bahncard and you can plan your trip in advance. But IMO, it the least we should expect from 2 neighboring countries.
I'm very excited to see the resurgence of night trains though, I love this mean of transport in particular!
Nice, I will be attending if the DB is okay with that. I don't have any practical knowledge in neither Nix nor Rust but I'm interested in both so that's a great meetup. Do you know if the speakers will talk in German or in English ?