This is a state level thing. As is whether IP produced outside of your job, on your own equipment, is yours.
I moved from New York to California a bit over 20 years ago in large part because I personally encountered this (the IP ownership bit), and preferred to live under California's rules.
It is worthwhile to read https://www.paulgraham.com/america.html. Point 7 talks about how easy it is for regulations to accidentally squash startups. I believe that the fact that California makes neither mistake causes us squash fewer startups. It is not sufficient to have made Silicon Valley a startup hub, but it was likely necessary.
I usually add this at the end of the agreement and if they wont go for it, I move on:
This agreement shall not apply to any inventions, conceptions, discoveries, improvements, and original works of authorship that [my name] developed entirely on their own time without using [the employer](s) equipment, supplies, facilities, trade secret information, or anything not based on or received from [the employer].
Agree it varies by state. My only first-hand experience was in a relatively conservative "red" state over 20 years ago. I paid for an hour of legal advice and the lawyer said that in general non-competes cannot be so broad that they prevent you from working in your profession or skill.
I moved from New York to California a bit over 20 years ago in large part because I personally encountered this (the IP ownership bit), and preferred to live under California's rules.
It is worthwhile to read https://www.paulgraham.com/america.html. Point 7 talks about how easy it is for regulations to accidentally squash startups. I believe that the fact that California makes neither mistake causes us squash fewer startups. It is not sufficient to have made Silicon Valley a startup hub, but it was likely necessary.