From the "redirect the vents" side of things, I've been doing this manually for the 7 years with no ill effects. Last year I added a Flair system and Ecobee to automatically balance using the registers. They have back pressure detection to prevent damage to the HVAC system so there's always enough vents open. At least in my scenario it's been a game changer for the third floor of our townhouse. As we've headed into warmer months our bedroom is actually cool in the evenings and the lower floors are normal temperatures. During the winter our living space on the second floor was cozy without blasting the bedrooms and making it too hot to sleep. With the number of vents I had it cost just over 1K to do, but that was way cheaper than it would have been to have the house and system rezoned.
I'm into smarthome stuff so now I've actually got room level presence detection going and tying that back to Flair with Home Assistant so we only cool or heat occupied rooms. Wife is a very happy camper in her now temperature controlled office, and it only targets the office when she's in it.
This sounds super interesting! I didn't know that smart vents were a thing. I'd like to get some more smart home tech stuff in general and this seems up my alley. Plus my vents seem to be stuck open anyway so it wouldn't hurt replacing them lol.