As far as we know Diable Jambe has nothing to do with Germa, his haki has nothing to do with Germa, Skywalk has nothing to do with Germa, his kicking skills have nothing to do with Germa. He got all of those and became powerful up until this point (stronger than all of his siblings by a large margin) without Germans help whatsoever (to our knowledge)
The best qualities he listed had almost nothing to do with strength lol
“He isn’t fit to be a soldier” because of his personality not his power. If it was all about power then Judge would’ve accepted Sanji as soon as he bodied Yonji but that didn’t happen
He isn’t becoming a full on Germa because he still has his emotions and can disobey Judge