Also, IIRC, if any product was made per that patent, or arguably related, there may be copyright issues, too.
One problem is 'patent trolls', wrangling whom will cost you so much in legal fees, that their sprawling patent portfolio is effectively off-limits.
Your patent attorney must find a safe, yet affordable path through such swindles and pitfalls, or warn that your plan simply will not fly.
When you take into account 'soak' testing and eg UL approval, sometimes you gotta shake your head and buy in established tech...