> As in Unix signals? tbh those seem ugly too; sigwinch, sighup, etc ought to be connected to stdin in some way; it'd be nice if there were a more general way to send arbitrary data to processes as an event

Well, as the process can arbitrarily change which stdin it is connected to, as stdin is a file, you need some way to still issue directions to that process.

However, for the general case, your terminal probably supports sending sigint via ctrl + c, siquit via ctrl + backslash, and the suspend/unsuspend signals via ctrl + z or y. Some terminals may allow you to extend those to the various other signals you'd like to send. (But these signals are being handled by the shell - not by stdin).