Transportation
 

We will start our trip in Lisbon but end in Porto. We do not plan to rent a car. What is the best way to travel about? Is there public transportation from Lisbon to Porto?

you will find rome2rio
seat61.com
https://www.cp.pt/passageiros/pt
useful tools to help your planning

If you prefer the bus, the national bus carrier is rede expressos.
https://rede-expressos.pt/en

Have travelled numerous times between Lisbon and Porto, prefer the AP train ( first class) , more comfortable, with washrooms and a snack car.
If you buy the tickets in advance they are discounted.