Having got one of these and (sort of) got it working on a Pi-top via a pi-topPROTO board - treating it as a HAT. This works providing you download and install the latest pi-topOS before connecting the PULSE - otherwise the pi-top won't start properly. The instructions do not mention this way of connecting the PULSE though the methods given in the instructions are not workable with the original pi-top as it does not have the mag-rail and connecting straight on to the Raspberry-pi prevents connecting the hub. The installation makes the pi-top speaker unusable without restarting pi-top OS, so you can't use it as part of a Stereo pair with the PULSE speaker.
The Alexa feature works after a fashion. you can only access it from the pi-top dashboard - not the desktop. There seems little control on this application. I have an Echo Dot which knows I live in Torquay - But the Pi-top version thinks I live in Seattle even though it is linked to the same amazon account.
Hopefully some of these problems will get resolved as the system develops