I’ve long dreamed of going from Europe to New Zealand by train and boat, but that route is not currently practical / ethical. ( fwiw, I used to know it well, in more friendly days I organised the ‘climate train to Kyoto’ )
Further south people used the ‘silk road’ route across the Caspian sea - until Azerbaijan closed land borders.
(note: for info about crossing borders in central asia the forum on caravanistan can help).
That leaves only the route via Turkey - Iran - Pakistan - India, which is possible (depending your passport and visas) although it’s dodgy across Balochistan. And then, after India, there is also a war in Myanmar. So, can only hope for better times.
Azerbaijan has a train line to Turkey via Georgia. Obviously ethical is a problem, but it is certainly possible in a relatively save fashion, if you have a good passport.
As I understood all the land borders of Azerbaijan are still closed, since covid, at least until october - so is there still any train running ? Maybe a deliberate policy to keep out enviro-ngos and ‘hippy traveler’ types who might carry infectious democratic ideas (including to the COP)?