Have you considered using solid surface materials in slab form? Silestone and Dekton makes cladding in a thinner slab than typical slabs used for countertops for architectural purposes and wall covering.

Not sure it would be any less expensive than large format tile, but it's worth looking into. Note, however that you need a really good framer and installer. The walls have to be plumb to make tthe installation look right.

We have microcement in all our bathrooms, which doesn't help you here. :-) We ended up stucco-ing our fireplace in a "freestyle" finish, which is mostly smooth but with some minimal texture & had it painted to match the walls. Truthfully, it doesn't look all that different from the microcement finish.

Link to the stucco finish: https://totalwall.com/texture.html

I would never put fake plastic stone there I think if you want that look the microcement is the answer but please check references before taking that step. IMo the only way to get the look you want other than the mitered large format tile and those require a fabulous tiler .

Use a smaller tile, 24" x 48", for example, and see if that changes the math to your liking. With the right color grout and the right color tile, I think you would be fine with some grout lines

You can stucco a layer of microcement yourself or get a guy who does drywalling to do it. I did something like that to the outside of my husband's office building. I used the brush of a cheap car snow remover to add nice brush vertical brush lines. Was a lot less expensive than buying a stippling paint brush.