How to create platform_override.ini

Questions
1

Hi all,
I am new to the world of platformio. I have imported successfully the source code from Aircoookie in VSC and I have some basic questions about modifying an existing usermod.

  1. platformio_override.ini
    My board is esp32dev. I want to compile and upload for example the LCD screen with the rotary encoder. According to the instructions I copy/paste into platform_override.ini the sample:
[platformio]
default_envs = WLED_tasmota_1M
[env:WLED_tasmota_1M]
board = esp01_1m
platform = ${common.platform_wled_default}
platform_packages = ${common.platform_packages}
board_build.ldscript = ${common.ldscript_1m128k}
lib_deps = ${esp8266.lib_deps}
build_unflags = ${common.build_unflags}
build_flags = ${common.build_flags_esp8266}
; *********************************************************************
; *** Use custom settings from file my_config.h
   -DWLED_USE_MY_CONFIG
; *********************************************************************

and then I add:

  -D USERMOD_FOUR_LINE_DISPLAY
  -D USERMOD_ROTARY_ENCODER_UI
  -D USE_ALT_DISPlAY

QUESTION: What is the [env:WLED_tasmota_1M]?
If I insert
[env:esp32dev]
I get
Error: Unknown board ID 'esp32dev'
If I insert ( i found this in another question in the forum)
[env:franz_esp32dev]
it compiles fine.

  1. Where is my .bin file?
    After successful compile I get:
...
...
Retrieved `.pio/build/esp32dev/firmware.bin' from cache
============================================= [SUCCESS] Took 9.57 seconds =============================================

Environment    Status    Duration
-------------  --------  ------------
esp32dev       SUCCESS   00:00:09.566

but all my WLED/build_output folders are all empty!

  1. How does upload work in general?
    I suppose I find somewhere the .bin file. Then I will upload it, I expect to see some configuration menu in WLED usermods menu. Now let’s say I want to change something in the same usermod, I recompile and I reupload the bin. What happens then? Will the upload replace my previous version of the same usermod?
    In the same way, if I compile the source code of the latest WLED and I make a small change, like increase the number of buttons, what happens after uploading the new bin? Will my previous WLED (with all my custom usermods) get erased with all its configurations or it will just increase the number of buttons?

Sorry for the long post!

2

https://docs.platformio.org/en/stable/projectconf/index.html