Onyx is way too soft to use for a floor. It will scratch with sock foot traffic. It’s also highly porous and stains easily.

Do anything else.

Is there an acceptable alternative? This tile took my breath away, and will pair nicely with cherry wood floors. Hoping it has enough variety that scratches and stains (see Zumi's comment) won't be too much of an issue. I also like reclaimed French terra cotta, but it would also be porous, and I'm not a one-percenter. Regular terra cotta is too orange.

This is the wall tile in 3 x 6. The largest available is 3 x 12.

Onyx is not a floor tile. It is a wall tile. There is a huge world of tiles out there, if you are looking for something burgundy. Look at Daltile Stencil Berry, in the full smooth matte. It is floor raged, unlike it's ribbed wall tile brethren. I'm using that in a restaurant remodel right now. Stencil - Berry (daltile.com)

I appreciate and value this advice. Defensively, I would point out that my selection was reinforced by the tile appearing on a bathroom floor in Architectural Digest (May 2024, P. 79). According to the company, it is floor-rated.

There are plenty of things you will see in magazines or on Pintrest which are pretty, but very impractical. You have to wonder what people would say about their choices a year later. I would look for an alternative for your floor as the other commenters have suggested. I prefer to use neutral tile so the background is flexible and still stands up in twenty years. Maybe wallpaper would give you the punch you're looking for. Then when you're tired of it you can remove it and do something else.

Okay, people! You've convinced me. What about cherry hardwood throughout, with the tumbled red onyx 2" herringbone (or hex?) for the shower floor only?