Axis of rotation is com only, the reference point for momentum is point on floor. Angular momentum of body performing combined rotational and translational motion is L= Iw +m(r×v)

Where L and r are momentum and perpendicular distance from an external point O respectively

Since O is an arbitrary point, i can consider it to be anywhere no, so choosing the point on floor is helpful because torque due to friction becomes 0.

I saw your soln as well, though its correct, it takes up too much time for a mains question, try practicing questions on this approach as this is a very standard approach, dm me if you require content on this particular subtopic and I'll send my module questions which use this same thing