Unicode has a lot of old "markup" symbols in typography, like the right pointy finger ([1], example in [2]). I see the external link symbol as a widely-used markup symbol of the current age, and it could reasonably be in Unicode.

[1] https://emojipedia.org/white-right-pointing-index/

[2] https://i.ebayimg.com/images/g/t60AAOSwAPVZDOK3/s-l300.jpg