Where is the bootloader_init() source code for the ESP32?

In the ESP32 bootloader_start.c, you can see that bootloader_init() is called during bootloader startup:

if (bootloader_init() != ESP_OK) {

The implementation of bootloader_init() is sightly harder to find because it is not located in components/bootloader but components/bootloader_support, within a specific platform-specific subdirectory, for example in components/bootloader_support/src/esp32s2/bootloader_esp32s2.c for the ESP32S2 – Github link to the v4.4.1 source code.