This question is in the context of a general bathroom remodel, but thanks for the advice.

This may be helpful in multiple ways because I currently use a bidet attachment and my concern was how I could continue using it given that tankless toilets look incompatible with mounting the attachment. I already knew about toilets that have integrated bidets, but wrote them off because I feared they would not be appealing to future buyers (I am located in the US). However, if a bidet attachment was never going to work on a tankless toilet, then I would be getting an integrated bidet because I can't go without a bidet.

Forgive me and my zero experience. I watched one manufacturer-produced installation video on youtube and the toilet appeared to have a supply hose coming from the wall like most toilets do. Why would supply plumbing need to be changed?

That's too bad. I would have to find one that doesn't really have corners and you make it sound as if that's the exception to the rule.

I don't know what qualifies for commercial grade, as the pictures I've seen strongly imply they are built for residential use, but I am certainly talking about a truly tankless design. The flushometer design so often seen in public toilets has long been a dream of mine because of their seemingly superior performance, but that obviously has nothing to do with my motivations for wanting to rotate the toilet.

I have zero experience in home maintenance. Everyone starts somewhere and the top of the list for my situation is several bathroom items. So, could you explain what "rough in" means for this specific situation? I think I understand it from doing a quick google search just now, but the principle behind my original question was to see it is possible to rotate a toilet with the drain pipe as the axis of rotation and still have it function.

It was my hope to not have to redo plumbing, but if necessary and not too bad, I would do it. I assume you mean that the flange would have to come off the piping and then replaced at the same angle as the toilet?

The reason is very sane and normal, but in my experience, redditors tend to go on side tangents that have nothing to do with my question. Ever since yahoo answers shut down, I have been on reddit, treating it in the same way. Quite frankly, I don't know how so many people have so much time to have reddit discussions just for the sake of discussion.