I'm assuming that if I wanted to integrate my own the svg

I'm assuming that if I wanted to integrate my own the svg and png sprites into an upfront starter theme - I would have to generate a new one and add it through the Media Library - as opposed trying integrate into the one provided in the starter themes.

Can you confirm my assumption?

Can you share the exact workflow of how those sprites were generated?

I believe this link
https://css-tricks.com/svg-sprites-use-better-icon-fonts/

to be the best resource however I'm curious to know wpmu's workflow specifically.