Room divider - one-sided or double-sided?

clearly bilateral

Walkable on both sides. Otherwise, you could have had a wall built right away.

I wanted to keep it flexible .... but thanks.

What minimum passage widths would you maintain .... 85cm on both sides? (on the fireplace side I would of course start counting from the beginning of the fireplace)

How wide is it from the fireplace to the opposite wall?

I already suspected a sensation from the headline: A room divider that is only perceptible from one side of the room and not from the other. Regarding the specific question: bringing it forward on both sides does take up space, but it is nicer.

Which clearance dimensions would you minimally maintain

As wide as possible, but still symmetrical (meaning both sides are equally sized - measured from the chimney)

and think about the fire protection around the fireplace. Don't make the passage into a trip hazard (placed glass plate).