Raspberry Pi 5 or Raspberry Pi 4 with power supply (neither the Raspberry Pi 3 Model A nor Model B have enough RAM to be stable).
I suppose it really depends on the amount of integrations your add to home assistant.
You could always use an older version of home assistant as well to tinker if the newest versions are not stable on the older hardware.
No need to expose your home assistant to the internet if you have a older install, if you are worried about security. Accessing through a VPN should be safe enough.
Pihole is great. Then add unbound and it’s even better.
Does it run on an RPi 1?
They state on their homepage:
I suppose it really depends on the amount of integrations your add to home assistant.
You could always use an older version of home assistant as well to tinker if the newest versions are not stable on the older hardware.
No need to expose your home assistant to the internet if you have a older install, if you are worried about security. Accessing through a VPN should be safe enough.