One feature that I always liked in vim as a French speaker working with qwerty is the ability to input special characters directly in the buffer using digraphs. I decided to extract this functionality in a standalone command-line tool called digraph so it can be used directly in the shell or in kakoune through piping. I find it really useful when writing email in French.
Since, as opposed to Vim, the use of digraphs is non-interactive, a placeholder character (#, but I intend on making this configurable) is used to signal them. For instance
fâchée after parsing.
Note that this project is still very young and that I have no prior experience with C, but it should already be usable as-is.