Well, it has some ceiling, some place. Is it the same ceiling as the master bedroom? Sloped and high?

You could install a recessed can light or shallow surface light or track light far above. Or hang a pendant that comes no lower than about 10 feet above the shower floor (Check the building code. The approved height is usually given as 8' above the rim on the tub, but you don't have a tub, so...). All lights must be approved for damp locations.

This is my favorite illustration of that part of the code...

And, you could install a lower ceiling. Not difficult.

How tall are the walls surrounding the shower?

Not sure how it met code, but here is an idea if you haven't built the shower yet....might write to the builder about the details.....

Like the picture with the small wall scones. Have been unable to source them. The picture below is the framing of the en-suite and closet. The pine ceiling is 18’ high and the walls 9’.

Drop the ceiling. 27’ is going to be freezing with no heat held in.

There is heating and a ceiling fan over the entire area. The floor is heated. Thanks for your concern through.

I don't know if outdoor wall sconces (rated for wet areas) would meet code in a shower, but maybe? Check with your electrician. Seems that what I see online allows it, just as long as it's "wet" rated and not just "damp" rated.

With sconces that are bright enough and high enough outside of the shower enclosure, I don't see that a fixture inside the enclosure is essential, especially with clear panels and door for the enclosure.

YMMV