Don't worry about whether it's gay or straight. Under the surface, we're all people. Just like cute things and if it makes you gay, so what. If it makes you straight, so what. The only person you have to answer to is yourself. Literally no one else cares what your actual orientation is, just be happy and be yourself.
As to Minami's identity, I'd say genderfluid if I was asked to guess? But in the end Minami is the only one who has the right to say. All the same I like to say Minami/Akira is trans sometimes just to piss off the wrong people for fun. Like the above I wouldn't worry about it too much. Minami is Minami. Cute magical girls are cute. And anyone, with the right app, can become one themselves! (Yes, you too! Cute magical girl!)
This manga is too wonderful for this Earth and we're blessed to have
Kashii Yutaka for making it and
@milleniumbug and company for making it accessible to us.
EDIT: Also Akira is immensely relatable in this chapter. And it's super cute they like Saku.