This may well be mumbo jumbo, it is certainly speculation, but there does seem to be a logical link to your speculation.

Universe = that which we observe, or can assume to exist as a logical extension of what we can observe.

Cosmos = everything that exists, or can exist.

I use the term cosmos to avoid any complication that might arise from saying that the Universe is both finite and infinite.

The Universe is finite; you have produced considerable evidence of this. Possibly its apparent finiteness could be a function of our limited ability to see anything beyond our 3+1 dimensions, but that is a side issue.

The cosmos is infinite (this includes eternal). In eternity there is no passage of time. The apparent passage of time is a feature of our restricted dimensionality.

In the dimensionality of the cosmos, everything that can happen is (happening) now.

Our Universe exists because it is eternally borrowing and repaying energy from/to the cosmos. In the frame of reference of the cosmos this is static, but we experience it as happening in linear time because we cannot see the whole picture.

There never was nothing.