I just recently built a new home and missed a few things...so....if it were me.
A neighbor building at the same time as me did most of this and paid about $5k to a LV Installer...materials & labor, prewire & trim.
I would prewire every room that will have speakers...home run to a central access point. Run for a pair, but you may decide later to go mono in a few rooms regardless.
Run Ethernet to everywhere there will be a TV and your HT space. (I regret not doing this)...wifi is great, but in a 100% streaming household with 6-8+ devices running at the same time...Ethernet is king.
6 zones...if you want wall mounted volume control, etc. that's a different animal from my experience, but from a mid level AVR with a Z2 & Z3, you can probably accomplish what you want for a reasonable price.
To ensure the power to connect up to 8 speakers with Z2 & Z3...an amp like this will work.
https://emotiva.com/collections/amps/products/a-800
I'm running my Z2 (family-room and Sunroom...4 spkrs) and Z3 (Master bdrm...1 spkr)...I can easily add more speakers to Z3 if I wanted to expand.
I can have a source going to Z2 & and a different source to Z3, and control both with the Marantz app or remote. But that's the extent of it....to gain further control of Z2, I bought a speaker control unit to give me on/off and volume control of the family room and sunroom individually. Both rooms in Z2 must have the same source, but I effectively created a sub zone.
https://www.ebay.com/itm/4-Channel-Multi-Zone-A-B-Speaker-Selector-w-Volume-Control-100-Watts-Channel/290816188150?hash=item43b5fedef6
In addition to the AVR, you've only added about $600 with the zone amp, and speaker controller.