That’s a different story altogether. You can work for someone else, however, if you do divulge something that is theirs then you can be sued. But you cannot be forced to not work at the same type of job, or even work at the same place you worked at with a previous employer. I work as a consultant, and have worked at the same place of business with several different companies. One company threatened those that went with the new company, but they were denied possession of us like chattel. 8>)
Consulting comes with some freedom, good money and some BS along with filing taxes quarterly.
And you can reverse engineer stuff, but they will fight you.
Especially if you get into their money stream.
America has a long history of after market improvements based on studying existing designs.
It aint easy though, once the bean counters smell lost money, here they come.