Urbit's programming language Hoon uses two character "runes" instead of keywords. Here's the standard library and compiler source, for example: https://github.com/urbit/urbit/blob/master/pkg/arvo/sys/hoon...

There's a full rune reference available at https://urbit.org/docs/reference/hoon-expressions/rune/, but tldr they're group into families, with the first character being broadly what it does. AST nodes that have to do with "conditionals" are ?:, ?., ?@, etc.

I don't think anyone uses non-ASCII diagraph fonts for them, but it wouldn't be a big jump.