Hi Matt,
I think your research would best be placed in its own topic in this forum. As @Jojo-A rightfully said it does not make sense to pollute this feature request with discussions about the optimum system for you to use.
You may leave a link here to your new topic once you created it. If you have specific questions re KNX you are also welcome to post them as comments to the KNX Cookbook guide in this forum.
This being said, I think that another option for you would be HA with ESPHome microcontroller nodes as user interfaces, sensors and actors. They can communicate based on WiFi. But if you wan’t them wired instead of WLAN based, this is also easily possible by using standard CAT-7 cabling with POE (Power-over-Ethernet) power supply. The only thing you have to decide now is the kind of cabling that you put into your walls. This will be very different for CAN, KNX and IP based systems. Different in terms of cable type and in terms of topology (line vs. star vs. mesh …). Everything else can be changed and improved later but the cabling is close to impossible to change once your house is built.
But as said: Better open up a dedicated thread for discussion.