Home Assistant is a Python-based open source smart home system that supports smart home devices of many brands and can easily implement voice control and automation of the devices. You can run Home-assistant on the Raspberry Pi, without having to send your data out onto the internet. This means that you have total control over your data, limit the amount of internet traffic from your smart devices, and tighten up security.
And RasPad 3 is powered by Raspberry Pi 4 with 10.1" HD touch screen and 5 hours battery life. We also wrote scripts for it to boot up and full screen self-start, so you can use Home Assistant on RasPad more easily and quickly.
Here are some projects made by others that combine Raspberry Pi and Home Assistant.
My cheap smart home system | HomeAssistant Wall Panel - AGT Designs
DIY Home Automation Intruder Alarm System! || Home Assistant + Raspberry Pi + ESP8266 - GreatScott!