I would say fuck the rules and just don’t let them find out. Do what’s best for you. The siren sure won’t

i was a waitress/server while working at the bux. i think being a server is a solid choice!

As long as it's not another coffee shop/somewhere that you would be working as a barista you should be fine. Just think about if your trade knowledge from working at starbucks could benefit the competitor/harm starbucks; that's what they care about and would consider a conflict of interest. It's also a good idea to disclose your other job to your manager just so it doesn't cause an issue down the line if they find out.

i had a partner i worked with that worked night shifts at dunkin, so i’m not even sure if this is a legitimate thing since i feel like that’d be one of the sirens biggest competitors. but also idk

I think it’s just coffee bean and Dunkin they don’t want you at. Maybe other small coffee shops too but waitressing sounds fine.

Working at another coffee shop or a tarbux/krobux etc would be a competitor. Being a server sounds fine!

I have a coworker who works at sbux and at a restaurant and there aren’t any issues. Just disclose it to your SM just in case anything happens.