Visiting Frankfurt, Looking for Local, Traditional, or Modern Frankfurt cuisine (and unique culinary Souvenirs) Recommendations

Hi everyone,

I'm visiting from the San Francisco Bay Area and looking forward for a day or two of eating around Frankfurt. I'm looking for more local/traditional Frankfurt cuisine for breakfast, lunch and dinner but I'm happy to try anything.

Some things I read upon are the Frankfurter sausage, green sauce, apfelwein (apple... wine/cider?), and Rippchen. Are there recommended places to eat these items? Also are any of these items more for breakfast/lunch/dinner?

Also for high end Michellin type restaurants, I was looking at https://guide.michelin.com/us/en/hessen/frankfurt-am-main/restaurants

Any places suggested for a one night splurge that would be considered more unique.

I plan to visit Cologne, Amsterdam, Brussels, and possibly Luxembourgh for my trip if any cuisines might overlap.

Also are there any interesting unique snacks in Germany that is great to bring back and share?

Thanks!