Weird. My Google Pixel 9 Pro XL has 3 navigation buttons.
That's something that's customizable using the stock firmware.
Settings -> Display & touch -> Navigation mode.
My Google Assistant still responds to "Hey Google" or "ok Google" just fine as well on my Google phone.
My Matter (and Zigbee, and Z-Wave) hub is a laptop I paid 300.00 for almost 10 years ago, when I wanted something cheap for the semi truck.
I run Home Assistant on it now. I have both a $40 zwave USB stick, and a similarly priced Zigbee stick.
The software for the hub comes with HA. Just install the matter server
Their zbt-1 dongle can do either zigbee or thread, but matter does not technically need anything else. Thread does, but not Matter. Install Matter Server addon and you can use any matter WiFi device.