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.
Mince ! Il nous faut encore faire des efforts pour pouvoir faire par train le tour du monde en 80 jours…