To my surprise, I made some changes, repeated my process - but the update never happened.

That's when I found out the name of the binary file was changed from:
m5stick_c_plus to m5stack_stickc_plus

I haven't found any documentation on the name of the binary, but I assume it related to the board (and mine is still: M5StickCPlus).

I had been using library 2.0.4 but then upgraded to 2.0.7
and now I see the version changed to: 0.4.3
And the web page says to use the M5Unified version. For me that's
a bridge too far right now.

Arduion is version 1.8.19

Is there any documentation on the versions and how the binary names are created? I did just see this (thanks). https://docs.m5stack.com/en/platform

I especially need to have a binary that is the same memory configuration as my 2.0.4 M5 and ESP32 since the OTA has to work for 100's of installed versions.

thanks.