What were the first TWO things created in Genesis?

Well, yes, but ...

It seems to me that Genesis 1:1 would be a statement that includes time/space and matter/energy (and the forces and dimensions associated) all at the same time; all of which are necessary to make the universe ("the heaven(s) and earth").

I kind of look at it as a lump-sum kind of a deal, the "singularity" erupting into space-time kind of conveys beginning of passage of time as we perceive it, energy, and lots and lots of energy but without form, just as "Earth" was formless near that "beginning". I would instead of wondering what was "created second", would say once the universe began, time began, so did unleashing of energy, simultaneously, as such, "everything" already existed, but in different states. From the perspective of causality, the "second" thing to emerge after "beginning of time" would be space, albeit time and space are inextricably linked, so, perhaps that wouldn't be the second thing to be observed if one could observe the origins. But as you ask from viewpoint of Genesis, the next significant development worthy of notice would apparently be emergence of Goldilocks zone planets in solar system(s), all those particles which had to first coalesce from energy apparently weren't that spectacular of an event. I have to say "life-enabling planet" would be the second significant development.

heaven and earth

Gen 1:1 ¶ In the beginning God created the heaven and the earth.

The heaven would be the empty space you speak of.

What if leave time to a supernatural God for now , then there was Gods energy this gives rise to space and matter , life begins as mind body and soul the evolutional energy most call God , evolves to a point we can work it out interact with Gods energy increasing our goodness evolutional fitness , this allows for those that need miracles to pray to God and those that just require increased goodness reduced fear to interact with Gods energy .

search for goodness and string theory

This is just my guess - energy.

Energy becomes matter when it slows down. With the passage of time, DIRECTED energy would become matter - therefore the heavens and the earth.

nothing and something