Personally, I don’t recommend building Home Assistant on a Raspberry Pi as you’ll almost certainly outgrow it and need to invest in something beefier. That said, Raspberry Pi’s are progressively getting more powerful and now that you can use a USB drive rather than an SD card, you can avoid lots of problems down the road.
https://magpi.raspberrypi.org/articles/build-a-home-assistant-with-raspberry-pi