FBRef have both match reports.
7-0
0-0
Onana had 100% Save % with PSxG of 1.4
De Gea had 12.5% Save % with PSxG of 3.9
Both of them were very poor at dealing with crosses but Onana was worse (3.2% for Onana, 6.7% for DDG)
Average pass length was similar (38.5 m for Onana vs 40.6m for DDG)
When Onana hit the ball long his pass completion was slightly better than DDG (44.4% vs 37.5%)
He also hit it long slightly less often than DDG (51.3% vs 57.6%)
The biggest difference between them was their actions as a sweeper. For Onana his average position was 18m off his line. For DDG an absolutely pathetic 5.7m.
That last stat alone will have made a huge difference in helping to keep Liverpool at arm's length.