I don't think you'd want the moveable mirror AND the door still there. What if someone moved the mirror into place while you were in there? You'd be trapped.

Make something that IS the door, but disguised as something else.

A quick search

How about hiding it with a mini folded screen? https://www.overstock.com/Home-Garden/Handmade-Wood-Paper-2-foot-3-panel-Miniature-Windowpane-Shoji-Screen-China-24-x-36/3378762/product.html?kwds=&refccid=CZIJR445UYGIEE2C7CHQ4Q4CNA&rfmt=price%3A100&searchidx=9

well if you do a taller sliding door (like a regular height) why would you need to keep the current door? you don't need both. remove the door and just do a sliding door. when it's in place, it covers, when you want entry just slide it over. (this way no one can slide it back and lock you in)

or, do a mirrored door. this way when it's closed you'll have a full length floor mirror option (

(it's ok if it's taller than the opening. no one will see what's behind it)

you'd have to move that chest if you want this option.

Or, Why don't you make the door into a bookcase that opens?

it's on casters so it will roll, even on carpet, but it's hidden by the trim.

back to the sliding door. doesn't have to be a barn style. you can have a nice looking door

Do you have curtains on another wall? If so, you could hang the same ones over the door.

Great comments and ideas everyone. Thank you! I should have mentioned that the adjacent space isn't insulated very well so I prefer to keep a pretty solid seal on the door to avoid too much heat and cold coming into our bedroom. Therefore I didn't think we could do just a barn door or a bookshelf.

the bookshelf would be no less drafty than the door you have. insulate the back of the bookshelf (from inside) if you're that worried about it.

I mean, other than removing all of the door trim and painting it to blend in w/the wall, there isn't much else you can do w/it (other than all these suggestions. Not sure what you're looking for)

remove the trim, paint the hinges, paint the door, same as wall. get a less decorative door knob.

or, try removing the door knob, and install a flush mount or low profile handle. then you can do the sliding mirror option over it. (you won't have a door knob that juts. )

The door is actually kind of cute. It wouldnt bother me a bit. Hang a nice piece of art on it, and it wont be quite as noticable.

I have something like that in my bedroom. I put a dresser with casters in front of it. Easy to roll aside if needed