If you are using BitBucket Cloud you can create pr rules to include people into Review based on files change. And then you can create a user for a bot to monitor those PRs using standard BB notification emails. Of course if there is not much PRs bot is Overkill and human will be enough.

You can always “just” create a static script that pulls repo check diff for files and email people if something is found. This way you don’t link your solution to the git cloud offering.