What's the theory on how all the matter and energy prior to the BBT was first compressed into the size of a house (or whatever) to begin with? The rubberband theory? Where everything goes out and returns ... still need a starting point.
That is the issue being discussed in a lot of forums.
Some theorists extrapolate the observed expansion of the universe backwards to a single, dimensionless point at "time zero" and insist that there was nothing, no time, no space, no energy, nothing before that.
Others do not "buy" that everything came from nothing for no reason, and suggest that the extrapolation backwards in time does not properly go all the way back to a single point. Some are looking for what you mentioned, an oscillation process in space that cyclically has matter (and maybe space itself) get compressed and rebound into expansion. But, there are no mainstream theories that are well received on how that could happen, so far, at least.
The latest response of
some of the Big Bang Theory adhearents is to recognize that the Heisenburg Uncertainty Principal says we cannot measure (or otherwise know) all the parameters of the physcial state of a system that is below a certain (extremely small) size, called the Planck radius. So, before the universe is theorized to have expanded to the Planck radius (at the "Planck time" after t=0) the theory is claimed to not apply
by some. See
https://en.wikipedia.org/wiki/Planck_units for an explanation and the sizes of these Planck units. They are
tiny - nothing like "the size of a house" you mentioned in your OP. The Planck radius is about 0.0000000000000000000000000000000001 inch. But, that really isn't an explanation, it is just a recognition that the theory can't cover whatever happened before that time and size.
So, the current options seem to be (1) yes everything started from a single point, with nothing before it because there was no time (or anything else) before it, or (2) we don't have any theory for the universe before "Planck time". Of course, even after Planck time, the Big Bang Theory is not necessarily correct. It depends on whether quantum mechanics theorists have extrapolated the results of their atom smasher experiements correctly to astronomical dimensions. And, there are multiple problems in the quantum mechanical world with their current theories. such as where did all of the anti-matter go that the theory says should have been created in the same amounts as normal matter, and then it all should have annihilated itself back into pure energy (light photons).
So, in reality, the BBT is a "work-in-progress" and some progress will probably be made with the new Webb Space Telescope and the new techniques for measuring waves in the gravitational field coming from distant major events like black hole mergers.
Stay tuned, its an exciting time.