Wow this is super cool! I’ve always wanted to dabble more in night photography! I know Samyang and Rokinon both make good astrophotography lenses. They’re wide with a manual aperture and focus, but they’re cheap and sharp and I think some are designed specifically around astrophotgraphy (so they handle stars pretty well). Look into them. I’ve got one on my Amazon wishlist that’s been parked there for a few years now haha.
Getting your hands on different gear is always fun… but sometimes shooting with the “wrong” gear will give you better results and stretch you more as a photographer. So, while you not might be able to get “more sky” right now, maybe you can put the aurora next to something else as part of a different composition? Just thoughts 🙂