@Doggo one thing that you can do (if you haven't already) is to turn on and train (or turn of and then back on) the "hey siri" feature. I'm not 100% on if apple uses the voice print from that to improve their general speech recognizers performance, but that's a thing that they could do (and they probably do it).
Beyond that, it's probably very hard. The in the cloud nature of how siri / g voice / alexa work makes adaptation to specific users hard (usually what is done instead is that a