It looks like that requires a panel to move out of the way. I was thinking more like "zipper" (probably more of a contiguous interface), so closer to zero volume when attaching, then it "unzips"/splits and pulls the back of the suit open, into the cabin.

    |
    |     /\ 
    | to |  |  
    |     \/

I don't see why an intermediate airlock would be required, except maybe for redundancy/safety reasons if the "unzip" process went wrong.

Since the inside of the suit is already at pressure, you could just pop it open and step out.

The near-zero volume of the coupling would make things much easier to clean/isolate.