Lucio main here. I never tried to get the achievement but it just happened on Lijiang Tower.
Zac Ilios, Lijiang and Nepal are great to get it. Just boop them off and jump/wallride
Half a year ago I've been trying to get it for 2 weeks, when it finally happened. Then after a few days I was playing on my friend's account and I got the achivement for him in the first game