Is there an elegant, cross-platform, way to determine the latest Unicode version that a machine supports?
What do you mean by “system support”? The system is mostly pushing bytes along, the programming languages/UI ovaries tend to do all the hard work. So it is usually more interesting to see what those support.
Emoji support is probably the best way to demonstrate what I mean:
A simple example: if this (🐦⬛) renders as an image of a blackbird, your system supports Unicode 15.0.
A more complex example: if this (🧑⚖️) appears as a judge, your system supports Unicode 12.1, if it appears as a Person followed by Scales your system supports Unicode 10.0, and if you can only see the Scales, your system supports Unicode 4.1.
The downstream use case would be to avoid attempting to output specific characters for a user that wouldn’t see them correctly (i.e. if I want to output a blackbird, I want them to see it, or if I output a judge I don’t want them to see scales).
Is this “support” in the sense of “can this sequence of code points be rendered correctly to the screen”?
OS and font dependent.
Yes, in that sense (see https://lemmy.world/comment/770772 ).