Like what is shown here: https://github.com/me-no-dev/ESPAsyncWebServer#send-binary-content-from-progmem with a small sample shown below:
const uint8_t favicon_ico_gz[] PROGMEM = {
0x1F, 0x8B, 0x08, 0x08, 0x0B, 0x87...
How do they get the "0x1F, 0x8B, 0x08, 0x08, 0x0B, 0x87" part? What kind of software is out there that can do this?