In practice the interpretation of "related" that matters is the one done by a nervous VC or acquirer doing due diligence before a deal. Their definition tends

In practice the interpretation of "related" that matters is the one done by a nervous VC or acquirer doing due diligence before a deal. Their definition tends to be broad. On the other hand, what people worry about is source code, not ideas. If you can claim all your code was written after quitting, you're usually safe. Which means in the worst case you can just rewrite any app that seems promising enough that you'd be willing to quit your job to work on it. Another option is to ask your employer for an explicit, written waiver of any IP rights in a specific side project. But many employers will only do this if you're prepared to quit otherwise.