.pt is the real thing but you need a local company or a TM.
.com.pt is a worthless by product IMHO
Now that .es is going to be deregulated we can only hope Portugal will wake up and do the same. I don't know if the TLD is popular within Portugal but I believe the country is not so tech-savvy. On the other hand a business having .pt would sound legitimate to me since the extension is regulated and not open to anyone.