Ideally wired speakers perform better in commercial environments. Such as in-ceiling speakers powered by a Sonos Amp. Era 300’s are better suited for home environments as they are primarily a wireless speaker over Wi-Fi. Human bodies can cause Wi-Fi interference.  If you are unable to open up the ceiling; below are Sonos Outdoor speakers (which work indoors as well) shown with Sonos Amp. They can be wall mounted and come in white also.

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Two speakers will not give even coverage. Listeners near the speakers will complain about “too loud” while the distant listeners will complain about “not loud enough”. Your goal is to provide enough music to mask conversations from other tables, provide some music enjoyment, while not interfering with conversation at a table.

Here is some tech. If the tech scares you, the takeaway is spacing the speakers approximately every 3.0m. Pendant speakers are very effective in restaurants. You wander even levels throughout.

There’s no need for a left side of the room and a right side. Alternate left and right around the room such that every person is between a left and right speaker.

I'd be tempted to go with the Era-100 Pro speakers.  They can be wall mounted or sit on a shelf. Lots of features nice th have in a commercial space?

https://www.sonos.com/en-us/shop/era-100-pro-black