If you are planning to do something on your own and then apply for a start-up pass, unfortunately the catering industry is one of the industries that are prohibited from applying for a start-up pass

Without a PR (green card) there is no way to start a business in Singapore, not even in any industry. At most, you can go and invest in a restaurant owned by a local Singaporean

And if you are only a WP, you can only invest in the restaurant and wait for the dividends to be paid out, and you cannot participate in the day-to-day management of the restaurant. The WPs are prohibited from working part-time under the law

Any further questions are welcome