I only had 2 nights in Porto, 15 years ago, so my recs are out of date.
I’ll mention the traditional dishes we tried in Porto.
We had Portugese Duck Rice/ Arroz de Pato, and Espetada (skewers, which might include seafood as well as steak, which originated in Madeira but we tried in Porto)
I ordered a Francesinha, which seems to polarize HOs.
Porto is known for its tripe, which I didn’t seek out.
You might find this article interesting.