Not sure if the issue is with Chrome or my local config generally (bog standard Windows, nothing fancy), but the us-flag example doesn't render as intended. It shows as "US" with the components in the next step being "U" and "S" (not the ASCII characters U & S, the encoding is as intended but those characters are being given in place of the intended).

Displays as I assume intended in Firefox on the same machine: American flag emoji then when broken down in the next step U-in-a-box & S-in-a-box. The other examples seem fine in Chrome.

Take care when using relatively new additions to the Unicode emoji-set, test to make sure your intentions are correctly displayed in all the brower's you might expect your audience to be using.