How to punctuate an ellipsis after a full stop?

I am trying to write some dialogue where an ellipsis is used after a statement with a full stop. So essentially its not that the first statement is being interrupted, its that the next statement takes longer to think about, like a realization moment, if that makes sense.

Eg 1. "That sounds great. ...hang on, isn't that John over there?"

Obviously the example above is not punctuated correctly since it is quite confusing. I am also wondering whether the "h" in "hang on" above needs to be capitalized? Since my understanding is that an ellipsis can have a full stop on the end to signify an end of the statement as oppose to a continuation of the same train of thought.

Eg 2. "That sounds great.... Hang on, isn't that John over there?" VS "That sounds great... hang on, isn't that John over there?"

The issue being is that the meaning of Eg 1 is very different to either version of 2 because of which statement the ellipsis is in.

I suppose an easy fix for dialogue would be to break it up like this:

"That sounds great," said George. "...hang on, isn't that John over there?"

But then how about if trying to achieve the same outside dialogue, such as with unreliable narration?

Eg 3. There were 3 friends with them that night. ...actually it was more like 5, because George and John were also there.

Any suggestions on best practice for this?

The question is addressed here When do you put a full-stop after an ellipsis and are they used in reality in novels? and Ellipsis at the end of a quote and What is the proper way of using triple dots and spaces before/after them? and use of ellipses at the end of a paragraph, etc. (Google's list is HERE)

However, I don't think that any are definitive because the use of punctuation of ellipsis is a matter of which style you wish to follow. ... And there are several, equally valid, styles.

Whatever style you choose - or if you create your own - you should be consistent.

My pragmatic advice would be: "Have a look at various style manuals, and choose the style that is closest to the style that you think looks best."

The general style guidance on ellipsis relates mainly to the use for words that are omitted.(See https://en.wikipedia.org/wiki/Ellipsis#In_different_languages) The ellipsis pause, as common as it is, gets very little attention.

An example of typesetting is give in the Wiki article:

i ... j

k....

l..., l

l, ... l

m...?

n...!

(See also https://www.freelancealot.co.uk/Herald/2011/02/ellipses/ and https://communications.unu.edu/mues-punctuation and

In the case of using the dots of ellipsis to indicate a pause, the guidance should be taken as being the same as if the dots were an omission.

The "official" style guides all seem to agree that "..." is treated as if it were one word, but are often contradictory on the need for a full stop/period. Thus

"That sounds great. ... hang on, isn't that John over there?" looks a little odd - h should be capitalised as it begins a new sentence.

The following would all be justifiable by one "official" style guide or another:

"That sounds great ... Hang on, isn't that John over there?"

"That sounds great. ... Hang on, isn't that John over there?"

"That sounds great .... Hang on, isn't that John over there?"

That said,

"That sounds great... Hang on, isn't that John over there?"

"That sounds great. ...Hang on, isn't that John over there?"

and

"That sounds great.... Hang on, isn't that John over there?"

do not immediately strike the reader as being wrong as the lack of a space gives an immediacy to the words.