Changing the Wi-Fi on HomePod

There is an article which explains that the HomePod uses the same details as your iOS or iPadOS device, see point 2 bullet point 10, I had to select the Wi-Fi when I added a new HomePod mini as it didn’t automatically join the network but had picked up on one from next door.

https://support.apple.com/en-gb/guide/homepod/apde6dc8093d/homepod