I would like to utilize some of the built-in Flash memory on a T4.1. My application
uses about 200 kB, so most of the 8 MB is currently unused.

A pointer to either a forum thread that discusses using this memory, or maybe an
example of reading and writing to it would be helpful.

When Teensy Loader uploads a new version of the firmware, does it erase the
whole 8 MB, or just enough pages (what size are the pages) for the new firmware?

I'm hoping to be able to have some storage that is persistent across firmware

Thanks for any guidance.