^ All of the advice above makes sense except for one thing I'll take issue with: the 360 hinge is meaningless in some use cases and essential in others. If you're going to be getting a keyboard / mouse so that you can quickly convert to a desktop setup (especially if you go with the portable monitor as well, and I highly recommend doing all of this), then you definitely want the 360 hinge.
My "on the go" productivity setup right now is,
- Work laptop (13.3" HP ultrabook from a couple years ago with the 360 hinge and a thunderbolt port);
- Asus Zenscreen Go with a Thunderbolt cable,
- Logitech K780 keyboard; and
- Logitech Triathlon M720 mouse.
With just those things, I can effectively have an office-caliber setup anywhere where I have a power outlet and 3 feet of desk space (and even the power outlet isn't necessary if I'm there for less than 3 hours). And it takes less than 30 seconds to set up.
In your case you may want a different mouse / keyboard combo. I chose mine because in addition to my work setup I'm also always carrying my personal laptop (a Zephyrus G14) and those two peripherals allow me to switch between controlling my work laptop and my personal laptop by pushing a button (also the K780 has a slot where you can put the portable monitor and it acts as a stand). If you were going for a more portable setup, you might go for a K380 keyboard and an MX Anywhere 3 mouse. If you wanted to buy a keyboard and mouse you could just leave on the desk at home and only use when you're there, I'd say you should go for the Ergo K860 keyboard and the MX Master 3 mouse.