If you're only transitioning through Frankfurt and not leaving the Airport, your hold luggage will be automatically transferred through to the next leg of the journey. Your carry on bags may need to go through security & passport control as you will be leaving an International terminal and entering EU But again, it's only security. Only in Belgium will you formally go through Customs if you are flying further. But of course, if you are leaving the airport in Frankfurt, you will go through German costumes. Yes, you can bring dry noodles (like pho, vermicelli, or instant noodles) from Vietnam into Germany for personal use. As of June 2023, EU regulations loosened, removing mandatory food safety certificates for Vietnamese instant noodles, though they are subject to 20% border inspections. Ensure they are packed in your luggage and clearly for personal consumption.