The ram-cave

Roge and I, the translators of We Need More Yankiis, decided to use he/him pronouns for Dragona in the chapter for several reasons:

The only person who addresses Dragona with gendered language is their brother, and there is inconclusive evidence as to what they identify as. We have no official word on what Dragona's gender is, only narration from Jodio's perspective. According to him, they "love girly fashion" and get breast injections. Dragona is also revealed to have a penis, but they use very feminine speaking patterns in Japanese, including the very feminine personal pronoun アタシ (atashi). This is typically used by women, but it can also be used by very effeminate men.

Jodio uses the term 'nii-san' (兄さん), translated as bro, to refer to Dragona. This is typically masculine. In Japanese, it's not always a statement on gender to call somebody by a term that doesn't match the gender they identify with - it can just be reflecting how they like to present themselves. For example, Japanese fans commonly call Ermes 'aniki' (兄貴) because she's a masculine woman. Still, it's much more likely that this is him thinking of Dragona as a man instead of just being a more unique use of the term.

Dragona makes no indication of being uncomfortable being called a masculine term. While I personally doubt this is the only pronoun Dragona would be okay being called by, they have a friendly relationship with her brother, letting him call them nii-san to their face.

The only other clear trans rep we've ever really had in the series is the prisoner seen in Stone Ocean. Jolyne is just amazed at how well a person can transition, but the doctor (who is already indicated as being a bit unpleasant) misgenders him and says he was given hormone injections.

I can't really make any statements as to what Araki may have in mind with Dragona, but I think this sums up what the situation is as of Chapter 1 well enough.