The Belgian coach served a one-match UEFA suspension — earned for yellow-card accumulation during the quarter-final victory over Real Madrid — as Bayern Munich fell 5-4 to Paris Saint-Germain in the semi-final first leg at the Parc des Princes, with assistant Aaron Danks leading the dugout in his place.
"It was different for me to watch, but I would have preferred to be on the pitch, going with the emotion of the game and trying to help," Kompany said. "The staff did fantastic to prepare the team."
Despite the defeat, Kompany pointed to the volume of chances Bayern created as grounds for belief heading into the second leg at the Allianz Arena.
"We suffered but we were dangerous. Five goals away from home in the Champions League normally means you're out, but the chances we had made us believe."
Bayern trailed 5-2 before goals from defender Dayot Upamecano and Colombian forward Luis Díaz pulled the score back to 5-4, leaving the tie alive with 90 minutes still to play in Munich.
"If you've got nothing at the game at 5-2 then it's hard to make a case to turn it around, but being as dangerous as we were, I feel like it's about getting your head back in the game and taking our chances."
Kompany identified the fine margins between commitment and caution as the defining tactical lesson from the night.
"I've seen a lot of good defending today but the game is such fine margins — you either go full into the battles, or retreat fully. The in between doesn't work against that level of players."
He returns to the touchline for the second leg and made clear what he expects from the Allianz Arena crowd.
"We're at home with 75,000 people in the stadium. I want more. We want that weight to be there, and then the Allianz Arena is a place where anything can happen."