“Both akasa and vinnana are infinite. One can experience that (I have not) when one gets into the first two arupavacara jahna of Ākāsānancāyatana and Viññāṇañcāyatana.
Ākāsānancāyatana comes from Ākāsā + ananta + ayatana, which means it is “infinite spatial plane”. Plane does not mean a two-dimensional surface. I cannot think about a suitable English word; it just means “it is out there”
I’m surprised that you explain it very well without experience. I happen to experience it for a couple days and it’s as you say. It’s out there, explaining it in normal mundane words is not possible, when I experienced it as a thought of it as Nibbana as suffering there is so subtle that you have a hard time to recognize it.