Can I add other sports (like cycling to the training program?

Yes you can.

In Karel's program you can manually add low intensity cycling sessions.

Adding or Registering sessions in other sports disciplines may affect however your compliance score (ie not respecting recovery fully), hence doing too much other sports activities may have adverse impact on an optimised training program.

In Xavier's program you can also generate plans for biking or cross-ski activities.  The library of workouts is limited though, however it may help to fix dates in your agenda when you regularly do these type of workouts on specific days.