If the two teams meet in final, it will still end like the way Liverpool beat Chelsea to lift the trophy in the FA cup, but I know it will not be easy for Liverpool to beat Leverkusen with many goals but the game will end up with 1:0 for Liverpool to lift the trophy.
Liverpool is leading in the premier league competition and Leverkusen is displaying excellent performance in the Bundesliga, which are some of the things that made many people to rate the two teams among the strong teams that will battle for final, but Liverpool will win the trophy.
The potential for these two to meet in the final seems only a small possibility in my opinion, but if that happens then we will see a fierce match and as you said maybe the match will not end in the 90th minute of normal time, so far both teams are still fighting in the 16th round is big and the opportunity for both teams to continue to the next round is very wide open because both of them are facing weak teams, namely: Sparta Prague vs Liverpool and Qarabag vs Leverkusen, I personally am quite confident that Leverkusen can win easily over Sparta, while Liverpool will also have no difficulty to eliminate Qarabag from the European League this season, because the two have previously met in the group phase and Leverkusen managed to beat Qarabag in those two matches.
About the chances of the teams meet in the European League final, I tend to see Milan meeting either one team betwen Liverpool or Leverkusen in the final, so far Milan performance is still quite good in the European League after they were relegated from the Champions League this season, apart from that, Milan experience maybe it's still better than Leverkusen and on par with Liverpool when they play in European competitions so far, that's why I said above that there is a small possibility that we will see Leverkusen and Liverpool meet in the final, but whichever club will enter the final later of course, we really hope that the final match will be very exciting and that both teams will have equal strength.
Talking about who will make it to the final, it is probably difficult to predict, but talking about the candidates who will win the UEL title this season, Liverpool most likely have a very good chance because currently they are still fine, they don't have any problems with their players, only Mohamed Salah. Recently he has been absent frequently due to injury and I hope that when the UEL matches start again he can maintain his physical condition until the final round.
As for Leverkusen, I admit that currently it looks like a Bundesliga giant replacing Bayern Munich, but Liverpool's experience and the quality of Liverpool's players are much better than Leverkusen's, so whatever happens, I'm sure Liverpool will still get the UEL trophy.
Still, we have to patiently wait until the semi-finals to see who Leverkusen and Liverpool will be against and if these two clubs meet in the semi-finals, it looks like our hopes of seeing Leverkusen and Liverpool in the final will not be achieved.