Hmm... wonder if pawpaws could be an outdoor plant here... how much summer heat do they need? They're hardy to ~-25°C, aren't they? We usually only get down to -15°C, so that's no problem; it's heat requirements that are usually the issue here.
If I could do them as an outdoor plant I'd be interested in any of the low-annonacin KSU cultivars (Sunflower, Wabash, Potomac, Zimmerman,
Wells, etc). Not sure which would be the most suitable / tasty. I think Sunflower was the lowest annonacin cultivar that they tested, followed closely by Wells, if I remember right.