Not sure you really mean the compose mechanism provided by Xlib (and xkbcommon etc ...)? If so, this wouldn't work for all these emojis that are represented by grapheme clusters, ZWJ-sequences or are just "qualified". The result of a compose sequence is limited to a single "key symbol", which can only encode a single unicode codepoint.
Even for those emojis consisting of a singe codepoint, it would really miss the point. There are LOTS of emojis available, an emoji keyboard (or emoji picker) shows them organized in groups and allows searching for them.
Even for those emojis consisting of a singe codepoint, it would really miss the point. There are LOTS of emojis available, an emoji keyboard (or emoji picker) shows them organized in groups and allows searching for them.