if it were me, I would completely abandon the curbless shower.

Unless it is a first floor bath with handicap accessible door widths I see no reason for the added expense of a curbless shower. If aging in place with disabilities is the goal than the extra tens of thousands for a curbless is a great idea but other wise it is just an expensive aesthetic upgrade.

Why would adding a layer of OSB or plywood in the rest of the bathroom incur tens of thousands of dollars? Isn't it just a matter of screwing down another layer of OSB on top of the existing subfloor?

If I go with a curb, I'd like it to be as small as possible but still be able to support the fixed, glass wall. What would you suggest I build this curb with?

The aesthetics of the tile is also a concern for me. Maybe I need to ask a tiler for suggestions.

That looks like a terrible layout for a bathroom. Curbless shower is the latest fad. If someone requires a curbless shower, they also require a seat in the shower. There is an endless variety of medical equipment to accommodate aging in place if is needed.

If someone requires a curbless shower, that means they cannot handle a stair or stairs going into a home. That kind of eliminates the option of raising the entire room.

Sophie - Could you explain why you believe there isn't enough room for a curbless? I understand your statement if the drain was to exist along the long wall but the intention is to have the linear drain span the 34" width along the wall with the vanity.

What good is a curbless shower if there isn't enough room for wheelchair with grab bar access?

The height decrease from the shower entry to the drain must have a 2” drop. That’s 48” at the steeper allowable 1/2” prrvfoot drop. Placing the drain at the shower entry requires that the whole room be waterproofed and sloped as a wet room. It just transfers your height issue to somewhere else.

The entire Bath is designed incorrectly for accessibility. Start over. Get rid of the tub.

Before you go with that type of shower, I strongly urge you to spend a few nights in a hotel in the handicapped room. I used to live in hotels traveling around Texas with a crew of guys. We would roll in and take all the suites for a month or more at a time. The guy who got the handicapped suite ALWAYS complained about his bathroom being wet everywhere after taking a shower. But we learned quickly to ask for a normal suite and not the handicapped one. I suppose you could save the cost of the hotel by calling and asking about their handicapped room maintenance. Or you might talk to the head housekeeper.