OMG - so happy. I finally finished configured a custom streaming wake word on my Home Assistant Voice Preview. I know this is child's play compared to what some folks in this community do - but just had to share. It now responds to "Hey Alfred" so I can fully enjoy pretending to be Batman at home in my Bat Cave.
In case it's helpful for anyone else just getting started out with home assistant/esphome/etc. and wants a custom wake word - here's a set of high level steps.
Setup basic Home Assistant stuff - add Home Assistance Voice Preview, etc.
Use tater-assistant to generate a new micro wake word for me because I was struggling to do this myself. (https://github.com/TaterTotterson/microWakeWords)
Install samba share integration on home assistant
From my windows machine, download the .tflite and .json files generated in Step 2 to a local folder on your HA server via samba share
Install ESPHome in Home Assistant
In ESPHome - detect the Home Assistant Voice Preview device, customize the YAML file to reference your new models (don't forget to restore your wifi ssid and pw, and encryption key!)
Use ESPHome to flash/install to the device (I had to use USB to HA server option to get this to work correctly)
Test new micro wake word
Party like a rockstar