Dear Amirpitch,
Wa alaikum assalam
Please kindly note the usage of the preposition 'fi' in the following verse (same preposition used in the verse you shared 67:16-17):
"...and I will surely crucify you on (fi) the trunks of palm trees" (20:71)
Does this mean that Pharaoh was going to crucify inside the tree or on / around the tree?
Therefore, the Arabic preposition 'fi' does not always have to imply 'in'. It can also imply something outside or around. There are other examples of this usage in the Quran.
If we were to take the same approach to render verse 67:16 or 67:17, one will note that the implication would then be an entity having control over / around / on the heavens. It would then arguably be a far-fetched leap to infer this as evidence that God existed inside His creation physically.
Please kindly note that this is not such a fantastic interpretation as not only do we note the preposition 'fi' be better rendered in certain contexts in the Quran as on / above, it is also well established in the Quran that God ascended his throne ('istawa ala 'larsh' - 7:54) in context to the establishment of God creating the universe and the laws and taking power over it. This is further elaborated in verse 13:2 with the term 'yudabbiru l-amra' (governing / disposing the affairs). This is God's 'active involvement'.
Furthermore, there is also some room to interpret the 'Who' as being the exalted assemblies that perform God's work who would then be part of the creation.
Either way, the overarching meaning is the same, whether it is the assemblies operating within the universe at God's command or God's command over his 'samaa' (universe) it is God's decree, His power and absolute control over the affairs of the Universe which remain at the gist of the message.
I hope this helps, God willing
Regards,
Joseph