Terrace doors, opening outwards

... you are basically right there, but for outward opening purposes, it is much better to attach latch hooks to the wall for hooking in, than if the door opens inward.

Googling "window opening outwards advantages" leads to a site from a window supplier that also explains advantages regarding rain, wind, and light incidence.

Always bad when a provider tries to make advantages seem appealing. I also don't see convincing reasons – burglary protection and weather problems with the seals are not mentioned at all.

And more light? Sorry, but how much more surface area would it theoretically be?

I can only speak from my experience that both the architect and three window manufacturers advised me against it. Reasons see above.

And as I said, if it were so great, more people would have it.

Thank you for your opinions! I think we will just stick with normal inward-opening doors. I planned it myself. I definitely wanted to be able to go outside directly from the kitchen. And the cooktop fits best in this spot. But we also have a terrace door right behind the island. And the door, which cannot be fully opened because of the island, I can at least open enough to slip through to get herbs. So I think I will manage with it that way.