A lot of London beggars sleep in London shop portals. What I mean is: they sleep outside the shop and its portal prevents them from getting wet when it rains. Also, they usually cover themselves with newspapers because they give them more warmth.
I’ve never heard the word portal used for that in AmE. We use the same word you did, ‘entrance’. I suppose if you want to get technical, the entrance is the opening, and the door is the thing you open.
Also, entranceway and doorway are used, but rarely. Doorway is used somewhat more than entranceway.
A similar word is portico. I looked up portal and portico. They seem to have overlapping meanings in architecture. They both refer to small covered entryways.
In AmE neither word is used by laymen. I have never heard the word portal used in this way. I have heard the word portico used but very rarely. In AmE we would just call it a covered entryway or maybe a covered porch.
Both words are related to portcullis and even porthole.