Kann ich die Avocado draußen im Sommer aufbewahren?

Yes! Do it! It’ll do about a thousand times better.

Just introduce it to direct sunlight slowly. Put it in the shade for a week, then a spot that gets some morning or evening light. Then more light. After that it should be safe to give it full all day sun.

Just watch the soil moisture levels very carefully. How often a potted plant needs water outdoors varies very wildly based on the weather.