Thanks to @timbosan, I've now got 2 HomePod minis that I've setup. However, I seem to have a challenge selecting them from an iPhone. I've done my research and tried a couple of solutions, but it seems to come back to one main issue. Mesh networks! I've a Netgear Nighthawk MR60 and unfortunately, the only solution seems to be having all Apple devices on their own non-Mesh network which does not really sound like the best solution moving forward!
Anybody else had issues (or not) and are using airplay on a mesh network?