A single amp should be able to power 4 ceiling speakers in that space just fine. I don’t think the neighbors will get too much noise though as they appear to be far away in your pictures, and your speakers will be pointing down, not at the neighbors yard.
I’d think a single Sonos Amp would do the trick but if you want maximum power sent to the speakers a Sonos Port and large (non-Sonos) amp would sure do the trick.
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