If a spin bike is most practical for your situation, I would recommend that you buy a cheaper spin bike and a set of power meter pedals. That way you will have an accurate power measure when using Zwift. It should be noted however that your resistance will not be controllable by Zwift and you will have to turn a knob to compensate for gradient changes during the ride.
There are quite a few posts about just how inaccurate the power calibration is on the IC8.
And a few on how to use a cheaper spin bike with power meter pedals like the Favero Assioma Unos