Check out the Positron! It's the most portable one I've seen. The guy behind it, Kralyn, been providing the plans to the community so you can make it yourself.

https://youtu.be/ZAPaOevoeX0

https://github.com/KRALYN/PositronV3

Since he's released it to the public, it's possible that you might be able to find someone else selling them commercially rather than having to build it. The latest version is V3. It's so small it can fit into a filament box!

I also travel for work and have been missing my mk3s back home. I've been eyeballing the Bambu Labs printer to bring on the road with me. My company will ship things around for me as I travel to different sites, so I don't have to worry about fitting it in a suitcase. I just have to worry about it being packable and shippable, which my mk3s in it's diy enclosure is absolutely not. The bambu is marketed more like an appliance than a project, in that it's practically ready to go straight out of the box. Presumably, this means it should be able to go back in the box and ship off to the next site.