Porto Santiago coastal route in 10 days

I think it is up to you!

There was just another thread on this same topic yesterday, and the answer is yes, in general.
AnaRosario is correct that this depends on you - most people can do it in that amount of time - people who hike slowly for whatever reason may not be able to do that. But search the archives, and you'll see lots of discussions about it.
Personally I think you're rushing it a bit - the hiking time is fine for an average person, but to fly in and out that quickly, with no cushion in case you want to take a side hike, spend an extra day somewhere, or spend more time in Santiago, gives me pause. I'd try to push back the return by a couple of days - then if you end up with three days to see Santiago and the area around Santiago, how horrible would that be?
If you really cannot extend your trip and end up behind schedule (which is totally contradictory to what the Camino should be about!), then there's always the possibility of jumping a stage to catch up, or walking a stage and a half one day and catching a taxi over a part of the 2nd stage of the day. The purists would boo and hiss at the idea of not walking every cm of it, but it is possible, and you'd still have walked more than the distance necessary to claim the compostela.

Here's one option that is both coastal and interior

Day 1 Porto to Vila do Conde
Day 2 Vila do Conde to Barcelos
Day 3 Barcelos to Ponte De Lima
Day 4 Ponte De Lima to Rubiaes
Day 5 Rubiaes to Tui
Day 6 Rest Day
Day 7 Tui to Redondela
Day 8 Redondelato Pontevedra
Day 9 Pontevedra to Caldas De Reis
Day 10 Caldas De Reis to Padron
Day 11 Padron to Santiago

This is exactly the time and route that we just completed only we stayed in Porto two nights and the first day we walked to Matasinhos and then took the metro back to our hotel. The following day we began in earnest by taking the Metro to Matasinhos and then on to Vila do Conde. Loved it!