Salam
I've been thinking about this issue. It maybe al is a specifier and in short means in Quran, the God that Mohammad (s) is claiming to be sent from.
It's usually said that "al lah" which put together "Allah" means "the God", and that "the" is a qualifier suggesting that there is only one.
It maybe there is no equivalent to the term "God' in Arabic. So everywhere it's rather saying "the God (I claiming to be sent from) is... ".
What made me see this potentially as a plausibility, is that there is a usage of the term "he is the God in the heavens and in the earth", there "the" is needed, as it won't make sense to say "he is God in the heavens and in the earth" but rather there is an expression to say he is a God in the heavens in a god in the earth:
Of course, that God is the Creator and there is no God but God. At the end, it doesn't change anything really, just that there might be more eloquence to read Quran in a way that suggests it's a specifier.
Why? It links up to verses such as:
"...to who you command us?" (objection by disbelievers to Mohammad (s))
"Lord of Musa and Haroun"
"Lord of this House/Family"
"Worship the God (which is) your Lord and the Lord of your forefathers Ibrahim, Ismail, and Isaac, a God that is One.."
And in hadiths and Du'as,
"And the Lord of the great light and high seat"
"And the Lord of the Prophets and sent ones"
etc..
It's a small difference, really. But it might open up doors. I don't know at the end. Will have to see and think about it more.