This app was mentioned in 7 comments, with an average of 1.00 upvote
Why did this get removed? This seems pretty relevant to Korea to me. Sure his particular situation is unrelated but given the prevalence of Hangul Office in Korea it's likely that Chromebook users here would be interested in the replies to this post.
OP if you're still here (do users get notified of comment replies after their posts get removed?) check out https://play.google.com/store/apps/details?id=com.infraware.office.link&hl=en It's an Android app (can those run on ChromeOS yet?) but it lets you work with Hangul files.
Polaris office allows this and is free. https://play.google.com/store/apps/details?id=com.infraware.office.link
Also Adobe reader allows for pdfs. https://www.droid-life.com/2015/01/13/sign-pdf-android-without-printing/
Polaris is a one time fee+optional subscriptions Reviews are a solid 4.3 stars out of 482,003 reviews.
Is there anything the free Microsoft apps don't do that you need?
If the developer is providing a good DeX-compatible app, then pay the dev.
https://play.google.com/store/apps/details?id=com.infraware.office.link
It's $40 a year. That's $3 a month.