Doing Trolltunga with bad knees? Shuttlebus?

Hi, I know lots of people ask about Trolltunga - but I'm in a special situation:

I happen to arrive in Copenhagen in mid September - so I want to arrive before and travel in southern Norway. Trolltunga immediately jumped on my radar, but I've seen how hard it is described.

My shape: 30F, w\ bad knees. Tore my ACL in my right knee in 2016 and did reconstructive surgery (yay skiing!), and 6 months ago tore my ACL in my left knee, still didn't do surgery (yay skiing x2!).

If it was just the right knee - I'd be in good enough shape to do the full hike: A year ago I did the Grouse Grind, 2.5k stairway of 800m elevation, took me 2ish hours, knees didn't hurt. But now with the left knee, I'm a bit unsure. I'm on 6 months of intensive PT and strength training and have really come along: I'm in enough good shape to (just now) starting to get back to (somewhat) play beach volleyball (without running/jumping).

On the one hand, I saw people mentioning knees hurting and slippery trail (slipping is not good when the ACL is torn), etc., and ofc the length of the strenuous hike.

However, I saw that it's possible to take a shuttle bus to skip almost half of the incline, leaving 400m across 10km to the top. Does this shuttle bus really saves that much?
If I take the earliest one, would you guys think it would be realistic for me to be able to do the rest in I guess 12h with lots of rests, taking the bus down as well?

Norway is far and it's such a good opportunity for me and I'm bummed about my knee :/