For me to use this room as an office, my first need would be to add lighting to make it functional. The ceiling light would be my first change to a fixture that provides clear light & much more light than the small hanging pendant which is too small for the space. I’d also change the window treatment from the light blocking levelors to a decorative shade or blind that can be pulled up completely off the window for maximum light. No drapes or panels since all the wall space is needed for furniture placement. Even though this is a 9 x 9 room, there’s only one 9’ wall & the roll top desk will take most of the wall. I’d place desk close to window along that wall. That position will provide the most natural light & not block entry to kitchen. A floor lamp with really good down light for task lighting could go into corner to provide light when sitting at desk.

Perhaps something like this could work for you...

You'll need a plastic mat to place over the carpet for your chairs to roll in and out.