I suspect it is synth-specific as to how much pause you get. I asked about something similar a couple of years ago (though can't find the question now) because I sometimes use NVDA to read poems that I have written but haven't memorised.
The only lengths of pause I can get with the two synth voices I use - SAPI5 Zira and Sapi5 Hazel - are the pause for a comma and the pause for a full stop / period. A semicolon seems to pause for the same length as a comma, and a dash doesn't pause at all.
I was hoping to find a way to combine pauses, such as a full stop followed by a comma to pause for a full stop and a half, or two full stops being double the length of one full stop ... but that just doesn't work!
when I did an audiobook of my first poetry pamphlet I went into a recording studio and recorded half of the poems read by me from memory, and the other half using SAPI5 Hazel. The benefit of doing that was, for the few times I wanted a bit extra pause, I could edit the mp3 file to insert an extra quarter or half second of pause. That sadly doesn't allow adjusting the pauses for real-time NVDA use.
I encountered a similar problem with a pair of Orcam glasses I used to own. They also pause for commas and pause longer for full stops, but that's as far as it goes.