Could you please post the floor plan as a separate bigger picture?

Why do u want nib wall? If privacy the frost the glass.

Good point Kate. What different/additional functionality are you aiming for?

What are the measurements of the existing shower recess? Your ensuite looks like it is a generous space, from the photos. Full measurements of the area would help with the correct perspective and suggestions for your question?

Zoomed as best I could 😕. Looks like the shower recess is between the two doorways. Measurements would help.

Floor plan

The shower recess Measurements is 900x2000

The floor plan doesn’t really tell us much. However you have a good size space with the shower recess being 900x2000mm. You can build a 1200mm long nib wall with glass resting on top. This creates a ledge for shampoos etc. the wall needs to be only 100mm wide, so the width of 900mm shower recess is still at 800mm. There is no need for a shower door, just have a 800mm walk in allowance. So 1200mm nib wall, 800mm entrance. A 1200mm long nib wall would be enough to stop water spray from entering into bathroom floor space. Why a sliding door?? If you definitely want a door, then have a glass hinged door that swings inwards.

Thanks I was hoping it would be wide enough