@robj20 I agree with
@b0rn2sk8 in that a mini PC will be better. RPis are great but because they’re modular the costs can outstrip an equivalent mini PC and they’re not necessarily better than the mini PC.
Whatever you get, you MUST put your zigbee dongle on an extension cable as USB somehow interferes massively with the Zigbee signal.
If you already have a PC or Mac then download the HAOS image and use Etcher or similar to burn it to the an SD card or USB drive so you can install it to your NVME drive