My essentials for travelling with my MPC Live:
* Korg NanoKey2
* Zoom H4n recorder/audio interface (for field sampling)
* Peanut electric ukulele
That said, if you've got a Nintendo Switch, get Korg Gadget. I had a ton of fun with it on my last cruise. Here's a track I made using it.
I also have most of the Teenage Engineering Pocket Operators, and am having a blast with the PO-33 K.O.! sampler especially. Here I am on a flight where I sampled the flight attendant's safety announcement, and jammed with it on my PO-32 Tonic and PO-33.
Another amazing piece of travel gear is the Zoom R8 recorder. It records 8 tracks, has a built-in programmable drum machine, built-in microphones that sound amazing, amp simulators, loads of effects, mixing capability, and is generally badass. Oh, and it runs for like years on 4 AA batteries.
Here's a love song demo I recorded on the R8 using an acoustic ukulele, the onboard drum machine, and a Korg Volca Keys.