Override targetPkgs in buildFHSUserEnv

For the development with the espressif-idf-toolkit and the esp32 I want to use arduino-cli from nix-packages.

In linux a fhs-environment is set up for this package.

# buildFHSUserEnv is needed because the arduino-cli downloads compiler
# toolchains from the internet that have their interpreters pointed at
# /lib64/ld-linux-x86-64.so.2

The default fhs-environment does not work with the esp32-toolchain, because additionally zlib is needed.

Normally I would create my own fhs-environment and put zlib to targetPkgs. But in that case the fhs-environment comes from nix-packages.

How is it possible to override the targetPkgs-parameter for the fhs-environment in arduino-cli?