I have relevant experience with both brands. I ended up buying the Aries G2 streamer. Sonically it’s very good. So was the Lumin. As far as apps? Frankly, I found both the Auralic Lighting and Lumin apps to fall well short of Aurender’s conductor app. (I own an Aurender in another system). As good as Aurender’s conductor app is, it also falls short of Roon which Aurender doesn’t support.
So, I’ve put Roon in this second system so I don’t have worry about the limitations of the Lightning app.
I wish I had direct experience on the Vega G2 vs the Lumin to share with you. But, based on the quality of the Aries G2, I suspect the Vega is quite good. Lumin is clearly also a very good choice supported by many users here. That said, I would say the presence of an analog volume control on the Vega G2 would, for me, be preferable. Good luck.
mgrif