Ok, found the way:

Visitors > Locations > Country widget (table)

does include Greenland as a listed country.

However, I'll leave this issue open until I figure out segments filter or it gets improved.

I haven't tested but gl should work? seeing visitors for us re gl

In the list of countries, just as with any other country, I think we only show like top 20 or top 50 which is why it might not be shown.

Nope, "GL" in Country filter does not work, I have already tried (and confirmed again just moments ago to be sure), returns 0 results (but should be 4).

edit: also tried "gl" (lowercase version, although this should be case insensitive condition)

It definitely works here. Checked the visitor log... with &segment=countryCode%3D%3Dgl

Nope, appending it in url and creating custom segment on-the-fly still returns no views.

I think I know now why I only have report in the chart, but not in pages. The access logs were deleted as per archiving configuration, so that's why page views are showing 0.

This could be helpful message in custom reports, if no results were found:

There is no data for this report. Likely the data has been purged because the regular deletion of old raw data is enabled and the date for this report is more than 30 days old. A super user can change this setting by going to Administration => Privacy.

Thanks for trying to help me here :)

@dev-101 FYI: I've added a new readable segment countryName in #13929. This will make it possible to create segments like countryName==Greenland