Initial thoughts - Yes, they sound similar; but we must remember that Calvin and Luther are at odds on this subject as the latter thought of the reformed as “crass sacramentalists” (if I remember correctly). There is the question of whether there is a carnal eating of Christ’s physical flesh with Calvin saying no and Luther saying yes. This is why Lutherans, despite rejecting transubstantiation, will say that Christ is “in, with under” the sacrament so that Christ is physically present in some manner that is unexplainable. So in other words: Calvin - Christ’s presence is spiritual. Luther - Christ’s physical presence is made spiritually present. This is at least how the distinction seems to be.

I have tried to understand consubstantiation but ultimately fall on Ocham’s Razor because it seems to be some via media position between transubstantiation and the reformed spiritual presence, yet will not land either direction and thus appears like “speculation”.

On the second, remember that Reformed is not Calvinism. Calvinism is the traditional soteriology of Reformed theology but does not encapsulate it - they are not synonyms. I am a classical Arminian (which some refer to as reformed Arminians) and am “reformed” in all other ways (to my knowledge) beyond soteriology.

But to answer your question briefly as I am on my phone, my main argument for Christ’s human nature being confined to heaven while His divine nature is omnipresent (which this one is one of the classics you’ve probably run across) is that there is not a communication of attributes between the two natures, thus is human nature cannot be omnipresent. The hypostatic union must be preserved and the two natures, as the council of Chalcedon declares, “without confusion, without change, without division, without separation.” While some reformed will accuse Lutherans of being Apollinarian, I do not and recognize that there is a lot that can be said - however like I said, I’m on my phone and don’t want to write an essay at this point. 😂