[alistairSH]

Not nearly 17", but I've found my iPad Pro makes a reasonable second monitor when traveling. It isn't really large enough to want to do work on it - I keep those windows on the main laptop monitor - but it works as a place to drop email/Slack/misc other things.

[Terretta]

I advocate this as well. It’s superior in almost all ways to the portable screens of which I’ve tried many, and you also have an iPad, ideally with cellular chip. :-) On many short trips you can leave the actual laptop at home.

[Jcowell]

The caveat is that to can’t be used without an Apple ID , making it unusable for work devices. (Amazing for personal devices though)

[byteflip]

Yea that’s been a problem for me when I don’t use my personal Apple account on my work laptop.