Kinhin is routinely used in Zen practice to break up periods of sitting meditation and also allow us to practice moving with awareness. Some us may be able to practice meditation (seated or otherwise) but struggle with walking. The speed of the walking meditation may also be restrictive. Many groups practice a very slow form of kinhin but in others it is particularly brisk!
In our Zen group we replace kinhin with mindful stretching or watching the movement of the breath for anyone who finds walking too difficult. If you are practicing alone, this is fine to do. If practicing with a group, you can ask the teacher what their preference is, but watching the breath has the benefit of being non-distracting to others.
If you are able to practice kinhin for a short time but not the total length (which is usually 10-15 minutes), then do what you can and rest. Again, making a teacher or meditation leader aware of your limitations is good.
Doing kinhin in a wheelchair may be possible, depending on the size of the Zendo.