to be fair the new coach of Chelsea deserves time at least one proper full season before we start to judge his work, and currently I feel that both teams are equal but if I had to pick one team out of these two for proceeding to the next round then I would pick Dortmund because Jude Bellingham is playing for them.
Lastly getting Ronaldo would be a huge blunder on Chelseas part, because these days he plays less and causes more distraction by his off field activities hence they should avoid this transfer and try for other players wholl be committed to their coach/club.
Every new coach surely needs sometime for having better results and surely this is also for Graham Potter but sadly his situation is not good because he is currently down in Premier League and have no enough chances into Champions League which are not good but if he can manage then surely losing in this season is surely not going to hurt them with they can do improved performance in coming season but for this all management needs to have few favors as well because without their favor new coach can't do any positive development.
But, as we are having rumours about Ronaldo possible transfer then surely look like things are not good for them as they want to achieve something good in this season as well, and they will go with this gamble as well even they all know how things ended into Manchester United with coach which is also not good for the Ronaldo.