Ask a terminal whether a glyph is defined by a font vs. directly in its own source code?

Many modern terminal emulators include definitions for box drawing glyphs directly in their own source code, and disregard the versions provided by the font when rendering the display. Is there a general way for a program running in the terminal to detect which glyphs are rendered this way? Specifically, if a program makes use of additional box glyphs that might not be widely supported, what's the best way to check if they're available? Perhaps in terminfo? My current use case is a small personal-use project written in Python using ncurses for the graphical component, so bonus points for something that plays nicely with those, but I'm interested in all solutions. ---- EDIT: As an example, here's a set of characters provided by [kitty](https://sw.kovidgoyal.net/kitty/) ; a comment in the source code indicates they're intended for Powerline integration: If we try to render the same glyphs in Konsole, though, we get this: The glyphs displayed by Kitty are defined by the terminal itself, whereas the ones displayed by Konsole are provided by whatever font it's configured to use. Is there a general way for a program running in some arbitrary terminal to detect whether we'll see the something like the former vs. the latter?