Floor plan design of a city villa with a hip roof approx. 190 sqm living area

No no, a chimney is not a wall, even less load-bearing, and should be decoupled from the rest. Otherwise, there is sound transmission. You place it against a wall. Nothing more. It does not replace a wall.

Total width? Seriously? I would think twice about that. First, I wouldn’t find it particularly nice, but rather bulky; second, in the house you actually use the balcony mostly for airing beds and otherwise prefer to go out into the garden; and third, you would shade your living room.