Those are upstream Debian changes. Well, not setting Wayland default or QAing it for rpi but still, most it's a Debian's team job
If you read the article, they developed their own(?) lxpanel clone for Wayland apparently, so there's some custom work there. Of course I wonder why that wasn't done upstream (or maybe it was, and it's just not spelled out).
Will be interesting if configuring a Bluetooth sink using PipeWire is less of a hassle than Alsa, which was really unpleasant. Having all the codecs on a Pi Zero is nice!
I've had a much more pleasant experience with Bluetooth under Pipewire, though fixing issues such as incorrect Bluetooth profiles requires understanding still-pretty-young projects like WirePlumber.