Because skimo is a weight-bearing sport, you’ll want to make almost all of your training weight-bearing as well.
What you say about leg power is true between cycling and skimo, but it doesn’t take into account all of the postural muscles at work when you’re on your feet. Also, skimo is very much quadripedal, not bipedal. Training your poling in concert with your legs is really important, especially with most races being held on-piste. If the poling surface is supportive, you can get very helpful amounts of drive from your arms. You won’t get a relevant training stimulus in cycling.
In general, you need to make most of your training as specific to the sport as possible. It’ll be tedious, but those laps on the local ski hill are the most specific thing that you have.
I love cycling, but it wasn’t giving me what I needed for skimo, so I’ve had to drastically reduce how much time I spend on the bike. I use it mostly for recovery and getting out with the kids. Sorry I don’t have better news!