Just like you can't necessarily afford to engage in the legal system, the legal system can't be engaged if they don't have a signal that there's anything there to engage with.
And in interviews you can still use the experience and talk about your contributions without releasing the product/ identity to your current employer, and your current company is incredibly unlikely to come chasing after you years later on things with no obvious connection to your real name.
This is the exact opposite of what you should do. As soon as you start working on a side project that doesn't overlap with your day job, you need to tell your company to get it added to your contract's list of excluded projects (meaning they've verified it has nothing to do with them, and you're free to do whatever you want with it).
Issues happen when you leave your job and launch a side project not long after, creating a bit of a surprise. But if you had disclosed it previously, your previous employer is shit-out-of-luck.
As I will keep saying it does not matter if companies follow up on their threat or not. It still has a chilling effect on people doing side projects which is the intended behavior. And a lot of people can't afford a legal battle even if they had a high chance of winning.