I snapped my acl when I was 16 riding dirt bikes and never had it operated on.
I skated pretty hard from about 18 till 25 and then took up snowboarding at 28 before having the LARS (google it) surgery at 30 years old.
In the years I had no acl I still did everything I wanted to but my knee would swell up after a big workout and was constantly filled with fluid. It was not that uncommon for it to pop out and straight back in which would result in a lot of swelling and about a week of not being able to walk properly. Only once when I was skating did it pop out and not go back in, I had to force it in and that was fucking painful for weeks.
In relation to snowboarding, it was my rear knee that was the problem, I think its better to have a bad rear knee than a bad front one. I never really had a lot of problems with it snowboarding except for a few occasions when I was traversing heel side. The knee would just collapse inward and instantly go back but it would mean a week on the sideline due to swelling.
So after 14 odd years with no acl ligament I had the LARS and now my bad knee is stronger than my good one. I love having a good knee lol.