The only, 100% certain way keeping your “Smart-Home” from being hacked, is by having a “Dumb-Home”.
Yup. When my Alarm company touted how I could access my home security system from my phone I told them in no uncertain terms they could either permanently disable that “feature” or I’d rip it out and find another alarm company.
The only part of this I would worry about would be "smart locks." I don't think anyone would care about getting control of my lighting system, thermostat. or even my entertainment system (they wouldn't learn much about me). So, no smart locks on my houses.
I've had a BSR X-10 lighting system controlled by my computer since all the way back to the Commodore Vic-20 days. Only problem there was a neighbor installed one too and selected the same whole house code as I had (there were only 16 choices back then and they worked over the power lines.)
Bingo!!
Zeus and Apollo (Magnum P.I.) for the Alarm System.
Smith & Wesson, Ruger, Remington or Glock for Takedown.
911, Cleanup, Row 27 and bring multiple body bags.