"here the fruit is sweet and tasty, the taste is weird, do not compare it with that... is not acidic..."
The same can be said about A. sericea and some other Rollinias...
I think it worth to buy these seeds, measure them and plant. In any case, you will be satisfied.
Anestor Mezzomo grows A. sericea and very praises its fruit.
By the way, Annona sericea grows in Misiones, neighboring Paraguay, Parana, Santa Catarina...
http://sites.unicentro.br/wp/manejoflorestal/9517-2/Probably Annona sericea and Asimina triloba can grow outdoor in your area.
I mean if seller's seeds less than 1 cm its no Biriba.
Do you have any small "uncommon" Annonas by Northern Argentina?
For example Annona nutans habitat mostly Paraguay and Misiones...