Ask the barman the direction to the closest landmark? Grab a cab? Get a map from the hotel itself?
I understand that walking around with a laptop isn't for most but trying to think like OP here, I want to suggest that for their goal, habits can change. They are plenty of good solution beside a mobile phone to be able to get around.
Regardless of what technical solution you decide to rely on, e.g borgbackup, Synchting or rsync, the biggest question is "what" do you actually need. You indeed do not need system files, you probably also applications (which can fetch back anyway) so what left is actually data. You might want to then save your ~ directory but that might still conflict with some things, e.g ~/.bashrc or ~/.local so instead you might want to start with individual applications, e.g Blender, and see where it implicitly or you explicitly save the .blend files and all their dependency.
How I would do it :
then I would iterate over time. If I were to often have to move and can't really iterate, I would make the entire ~ directory available even though it's overkill, and only pick from it on a per needed basis. I would also insure to exclude some directories that could be large, maybe ~/Downloads
PS: I'd also explore Nix for the system and applications side of things but honestly only AFTER taking care of what's actually unique to you, i.e data.