Dude! Lay off the Sonos koolaid a little lol

Sonos has some OK stuff. But nothing Sonos makes is a good value. You are paying a premium price for anything they make. This is the same for the other wifi platforms as well - Heos, MusicCast, etc. So I'm not just picking on Sonos.
This is fine when it fits the install well. But there are other ways to go about a WiFi audio system that are a better value or even hybrid Sonos to get better value using Ports & AMPS. [That includes cost up OR cost down systems].
Sonos doesn't have any secret sauce. Most everything on the market can work with ARC/eARC these days. Everyone has soundbars. And other companies have great WiFi systems too (Heos, MusicCast, BlueOS, etc.). As far as Spotify goes, yes the built-in interface is nice - but not everyone uses Spotify. And even if they do, most other systems auto launch the Spotify app when selected and is pretty seamless. No one thinks its an issue on any other system I've seen.

Again, talking about Daniel's future system. I got the impression (from his past and current systems) that he may want a little better than what an 'all' Sonos system could deliver. He also has no problem putting together mixed components to make them work good together. And with the walls being open and able to pull wire anywhere right now, an 'all' Sonos system doesn't make any sense but to Sonos fanboys. He might end up with Sonos sources for music streaming. But speakers & amps can be wired for universal right now.

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So many questions need to be gone over with the house layout and rooms.
Is there a central location a small rack can go? Is there a location in the rooms that wire can be pulled to from the TVs and 'potential' speaker locations - looped to the central rack as well maybe? Outdoor TV or audio system - maybe in the future?

Use 4 conductor for all your speaker runs, that way if something changes you are ready (self powered speakers: 2/power, 2/signal - no problem). 2 pulls to the TV locations (passive soundbars will have enough conductors for 3 channels). Subwoofer locations: double up the conductors or DVC woofer(s) - no problem.

And of course Cat6 or higher everywhere. EVERYWHERE. Don't forget potential WAP locations for your WiFi. To your doorbell location. And possible camera locations around the outside of the home. A blank plate under the eve doesn't look as bad as wire running around the eve of a house in the future.

And run a fiber cable from the outside point, to where you plan on having your central location at. A pre-made fiber cable will work - try to find out what connectors the local fiber ISP is using and order the same (LC, ST, etc.). If they change or get it wrong, you can always get adapters to change it. What is very important is the type of fiber SM (Single Mode) or MM (Multi Mode). I would think SM is what you will find for the incoming line (it is everywhere down here from all the different ISPs). But always check.