Doomsday Clock 12 MetaVerse query

So I’ve re-read Doomsday Clock 12 .... and I’m hoping that somebody can help clarify the narrative regarding the MetaVerse.

I understand the basic premise, I’m just unsure about some of the finer details.

The birth of the Speed Force caused Superman’s timeline to be ‘pushed forward’ and reality split in two. The ‘original’ universe, home to the JSA and which had a now-different version of Superman was ‘archived’, birthing Earth-Two and the then-main timeline, with Superman ‘pushed forward’ in time, becomes the central timeline : Earth-One.

I understand this concept up until the point that it is stated that this birthed the Multiverse.

How did Earth-Three and all of the other earth of the pre-Crisis multiverse come about (from the perspective of the MetaVerse?) Pre-Crisis Earth-Six didn’t even have a Superman, to bring about a divide in the manner described above.

Or is it that the Earth-Two which was created when Barry discovered the Speed Force is a ‘different’ Earth-Two to the pre-Crisis Earth-Two and was archived outside of the pre-Crisis Multiverse?

Earth-1985 is said to have formed at the end of CRISIS which would give the impression that the ‘archived’ worlds of the MetaVerse are ‘outside’ of all the DC local multiverses pre-Crisis or otherwise.

So, did Barry’s discovery of the Speed Force create an inaccessible archived copy of the original Golden Age world IN ADDITION to the pre-crisis multiverse which ALSO had a similar Golden Age world called Earth-Two?

J