Great news but HACS (or something similar) really needs to be officially integrated into home assistant out of the box.
The entire point of HACS is integrations don’t have to follow the rules laid out by home assistant. Integration would defeat the purpose.
That will always be a thing, but there’s also clearly a demand for non official integrations and Lovelace components.
HACS isn’t the most popular add-on because people want a lot of stuff that doesn’t play by the rules, they mainly want functionality that isn’t officially within home assistant and HACS is a straightforward way to enable that.
MicroWakeWord is a project built on the ESPHome framework.
ESPHome is a project for building, deploying and managing microcontroller firmware (such as ESP32 devices). So, because MicroWakeWord uses ESPHome, you can easily deploy it to your preferred device.
ESPHome is deeply connected inside HomeAssistant and therefore the integration is essentially OOTB - but you have to flash ESPHome firmware on an ESP device which will probably involve soldering electronics. There are some dev kits available that contain everything you need pre-built though (like this one - no endorsement)