You can shoehorn "this" anywhere you want it but in verses 7 and 16 it doesn't really work (those are the next two appearances of the word). If you have to then create an interpretive reading of "this, the actual one we can point to" you have created a meaning that the text doesn't have. Can we point our finger to the actual heaven? Is there another heaven we can't point to, so I need "this" as clarification? Additionally, you are positing a simple definition when 2000+ years of understanding has said specifically that that isn't the meaning. Many people also point out Gen 13:5 to show that the word means "with".This, the heavens... this, the earth...
Since it states “et hashamayim ve’et ha’aretz,” shamayim, actual heaven. aretz, actual earth.
Et = "this one", the actual heaven, the one we can point to with our finger. And the actual earth, "this one", the one I can point to.
How doesn't "this" work?
The trop also has no pause after the "et" so saying the meaning is "this, the [actual]..." doesn't work.
The p'sukim make sense without the word so trying to pin a necessary meaning on them doesn't work. Look at verse 21. Reading in "(and) this" doesn't add anything to the verse. In pasuk 29, the word simply doesn't fit. 40:19 and 20 also don't use it in a way that "this" would make sense. I don't see how "this" works in any of these cases -- Hebrew has a word for "this": zeh.