The only way to have no grout is to have slabs of solid surface material. However, if you get large format tile, and ensure that it's dead flat so you have no lippage, you will have very little grout to deal with. I have 12" X 24" tiles on my shower walls, 1/16" grout lines, and epoxy grout. I've never had to scrub it or had any discoloration.

I got my solid surface curbless shower in Transolid solid surface material at Bath1.com. Don't worry if they do not have the shower walls listed. I called and found out that they have them, but for some reason do not list them in their site! My contractor, Jim, did not put the subfloor on top of the floor joists. Instead, he cut the subfloor material so that it fit between each joist. The joist tops themselves become part of the subfloor, and you save a half inch to 3/4 inch in height, lowering the shower floor. Then, since a curbless shower is a dangerous thing that can overflow and flood your house, I had a room floor drain installed. Jim bought a Kerdi kit of sloped foam that is meant to make a shower floor. He installed that as the room floor. The room floor rises up slightly from the entry, where it meets the hall floor, peaks about two feet into the room, and then all slopes toward the drain from there. The floor does not at all trip me up, and I do drag my feet at times. He used Kerdi waterproofing and then tiled the room floor. So my bathroom is foolproof and cannot flood. Adding that sloped floor happened to bring the floor level up to the same height as the edge of the shower floor. He used Kerdi Fix to waterproof the seam between the shower pan and the room floor. The waterproofing of the floor continues 5 inches up the walls, behind the marble baseboard. Click on the photos to expand and see the whole thing. Houzz crops them.

The basic shower wall kit includes the shower up to the height of the molding just below the shower head. I ordered the extension kit to take to to the ceiling. I also ordered a piece of plain Transolid material to cover the ceiling and the corner molding to finish the top corners, but most people would not bother with that. I spent $3263 for all of the shower floor and wall components.

I had already purchased all of my plumbing (Strom) and grab bars (Jaclo) and so I could not use the other type of shower kit that Transolid sells. It is their New Construction kit, and it is for when you are building from the studs out, with no wall surface up yet. This kind of shower wall has a backing of aluminum mesh, which replaces the drywall that you put up for my shower walls. It is fewer steps to build the shower. I could not use it because these walls have a single shower head hole, holes for the handrails, and a single hole for the controls already in place and so you cannot use the plumbing and handrails I had. If you are going minimalist with the plumbing, it can work. Check it out. that set offers a dome top with lights, too.

The only caulk visible for the shower is the line between the walls and the shower pan. The rest of the caulk is behind the corner edge moldings. No grout. The only part that gets dirty is the trench drain in the front, and I took of the metal top of it, since I am not currently wheeling into the shower. I just step over the trench and the little ridge they put there to direct the water to the main part of the drain. The trench drain really only comes into play if you have a lot of water.

To learn more about solid surface showers and look at the other materials that are available, I suggest you read this thread. [Kohler Choreograph? Thread[(https://www.houzz.com/discussions/kohler-choreograph-dsvw-vd~3420698?n=216)

Look into Swan stone panels, Kohler CHoreograph, Maax Uline walls. They will all give you solid walls. If you prefer tile, there are many companies that do the larger format tiles 15x 35, or even 24 x 48. We just got a new product from Arquitex that is interesting and does large pieces cut to size...

Good luck!