Before you do this, please make a law that forces the manufacturers to replace the devices free of charge when they get bricked due to a security problem.
Also, it's not about making wi-fi light bulbs cost thousands of dollars, but if yours were on the cheap end, they are most likely garbage products with highly intentional planned obsolescence, and subsidized by data collection app you have to install, which is the whole point of making them in the first place. If such business model were to become unprofitable, I believe it would be a great win for the society (and the environment).
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[0] - https://www.theguardian.com/science/2018/nov/26/uk-firm-sold...