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
updates.

Thanks for any guidance.