Hi
To answer your question...yes, you can use two Sonos Amps. One to drive the front in-ceiling and the other to drive in-ceiling as rear surrounds. However, just because you can doesn’t mean you should. Please continue reading….
Sonos In-ceiling speakers are not recommended for front speakers. They are traditionally used as music speakers in a large room but can be positioned as overhead surrounds. Both applications require the use of a Sonos Amp.
Sonos In-wall speakers are recommended as front speakers in a Sonos Home theater (if not using an Arc, Beam or Ray) typically flanking the TV on left and right.
In either situation you will not get Dolby Atmos sound. The center channel will be what is called a “Phantom” center created by the audio intersection of the left and right speakers. Here again that would be difficult to properly create with in-ceilng speakers.
The front speakers when setup properly will give the illusion that the audio is coming from the view screen and not from overhead. That said In-ceilig speakers would not be my choice as front speakers.
If you can find a dealer who carries AMINA speakers, consider these for the ceiling. These are a unique, high end product.