I would place another plant (seedling) 6 feet apart and when tall enough chip bud it with another variety. Pawpaw has a very soft wood and extremely wide cambium layer so it is very easy to do even for the beginners. Forget about t- budding pawpaw it doesn’t work as good as chip budding.
I think that tree will be fine whether planted like it is oriented in the picture, or with the trunk straight and the top angled. That tilt will just be aesthetic and the new growth will orient to the sun. In 10 years it will just be a little character in the trunk.
If you must have it straight, plant the trunk vertical, pound a steel T-post next to the tree, and tie the tree to it to train it.