What exactly do you understand by a "pleasant" garden size? If the plots are scarce and demand is high, I wouldn't hesitate to make the best out of it. However, you should not expect a garden with a football field.
Scarce plots maybe. But high demand not really. After all, half a dozen plots are still available. 190€/sqm purchase price is okay for a very rural location, but not outstanding either.
Space requirements on the ground floor, upper floor: not yet finally decided, would like a total living area of 180m
Does that fit your budget and of course the timeline (start of construction 18 months after purchase contract)? When everything is settled, you’ve probably spent €750k all in. Apart from that, I find the plot attractive. It has nice spaces in all directions.
(House entrance could be placed in the north, garden possible in the south and west.
Although a garden in the south with a terrace is always praised to the skies, in my opinion a purely south-facing orientation is rubbish. The sun beats down all day and you hide under the roof or the umbrella. For example, if a terrace were possible in the north, I would find that great. In the afternoon/evening the sun comes wonderfully from the west. Perfect for mild evenings. I mean, just think outside the box for once.