I recently purchased this setup. A Tiny in One 23 monitor and a M83 with optical drive. The computer mounted nicely in the slot provided on the back of the monitor but the optical drive was too large to fit the housing provided for optical drives and didn't have the right connector in any case.
I have to believe that there is such a thing as an optical drive that fits this TIO Monitor. The description on the Lenovo's web site states that there is a slot for an optical drive and that the TIO 23 is compatible with all of the Tiny series desktops. The manual for the monitor has quite clear and complete instructions on mounting an optical drive.
However no one on Lenovo's support staff that I spoke to including teck support, sales and customer support seemed to have any idea what I was talking about or to have any familiarity with the Tiny in One Monitor/all in one concept. Tech support was unable to locate a part that would fit, sales said "we don't have that - try a third part vendor" and customer support said "You got what you ordered if you are not happy send it back"
I'm not going to send it back because other than this issue I really like the unit, I would just like to be able to mount the optical drive on the monitor as advertised.