Wrap unicode flag codepoints in a flag supporting font.

[blowdart]

Problem

Windows has for geo-political reasons avoided adding support for unicode flags, instead they render as the ISO country code. This means no Windows machines will display flags in messages if they're inserted via the unicode representation.

Describe the solution you'd like

In order to display flags on Windows messages Twitter uses a custom font. BlueSky could consider the same.

Embeddable fonts that support flags include

Noto from Google (no license indicated)
twemoji from Twitter (MIT licensed)
BabelStone (SIL Open Font License 1.1,)

Describe alternatives you've considered

Rewrite the character to an image. This would disrupt screen readers, and would not scale if a user increases the font size in the browser)

Additional context

As a bonus the fonts may support newer flag additions faster than the operating system support, for example the LBGTQ pride flag.
Conversely, they may ignore certain flags altogether,

[pfrazee]

We'll likely need to get to this at some point yeah