Quran 3:2

God, there is no god but He, the Living, the Eternal.

is the short and comprehensive answer to your question.

There is no deity prior to, apart from or besides God.

God is eternal. There is no time "before God" nor "after God". God has Been before the beginning of time and He will Be after the end of time.

Not even this, not speaking about anything beyond is observable through science but it is only known through revelation.

The disbelieving assumption that God was created and the question drawn thereof bites in its tail because any assumed per-creator would have to be created, too. This proves that this assumption is illogical, thus false.

Quran 3:2

God, there is no god but He, the Living, the Eternal.

is the short and comprehensive answer to your question.

There is no deity prior to, apart from or besides God.

God is eternal. There is no time "before God" nor "after God". God Was before the beginning of time and He will Be after the end of time.

Not even this, not speaking about anything beyond is observable through science but it is only known through revelation.

The assumption - which cannot be part of Islamic philosophy because it rejects abovementioned revelation - that God was created and the question drawn thereof bites in its tail because any assumed per-creator would have to be created, too. This proves that this assumption is illogical, thus false.