Group Zones question

Can someone clarify what devices can be grouped?
I have Roonbridge running on a Raspberry Pi. I would like to be able to also play through my AptX headphones and have it maintain synchronisation.
If I add a Sennheiser BTD-500 will it show up as an endpoint and will I be able to add it to a zone with the Raspberry Pi?

Zones can be grouped by playback type. Chromecast with Chromecast, Airplay with Airplay, Roon’s RaaT with Roon’s Raat, etc. You cannot group cross playback type.

What I mean is - is there a definitive list of what devices use RAAT? Like a Hardware Compatibility List?
I know that I can group my Squeezebox devices but not a Chromecast device I have.
Does the Sennheiser BTD-500 use RAAT and so will it group with RoonBridge?

Anything which is certified as Roon Ready. There is a list of Roon Ready partners here: