On paper Porto will win the battle over Shakhtar, in fact we can see and refer to these two teams both from the depth of the team and the level of their respective squads. actually, I don't underestimate Shakhtar. It's just that, in my personal version, their victory over Barcelona could be said to be luck. In the sixth matchday match, Porto will act as the host team. and as you said in this post, we both agree.
Likewise if we refer to the odds that the bookmaker gives. there is quite a significant difference, Porto with @1.49 and Shakhtar with @6.40. It seems clear, from the odds factor we can also see the comparison between these two teams. Apart from that, in the first leg meeting Shakhtar lost with a score of 1-3 at their own headquarters. So it would be very natural if Porto were given more priority in the group phase meeting later.
It's just that Porto shouldn't underestimate their opposing team because after all, Shakhtar is in fact capable of overthrowing Barcelona. So, there always has to be thorough preparation to play the deciding match later. however, it seems that this match will not be as interesting as the matches in other groups. In short, my estimate is that Porto will accompany Barcelona into the next phase.