[iberator]

It's nearly impossible to know or to implement all utf-8/16 as beside of UTF support you need also to provide fonts for each. Thousands of scalable fonts - takes a lot of memory. That's why using such characters is risky as somewhere on the path such font will be displayed aa trash. (logs to email to presentation to word to excel to csv to database for example)

For years Ł support on Python on windows for example broke sometimes when imported from poor quality Excel files haha

[RobotToaster]

Normally there's a single "font of last resort" that's used for particularly obscure characters. Although even those don't cover everything, the extended Egyptian hieroglyphs don't display for me, for example https://en.wikipedia.org/wiki/Egyptian_Hieroglyphs_Extended-...

[cormullion]

a single font can contain a maximum of about 65000 glyphs, but there are over 150000 defined Unicode glyphs, so a single font of last resort isn’t possible, unfortunately. Complete coverage would require multiple fonts.

[RobotToaster]

I've never looked into this in detail before, you're right, it looks like android has over 100. Although composite font representation is supposed to fix this.