Apple M1, SDK v2.5.2, toolchain-supplied Python uses system-installed site-packages

Question

MacBook M1. Latest macOS. SDK v2.5.2. Building blinky w/ CONFIG_BOOTLOADER_MCUBOOT=1 enabled.

Doesn't matter if I start an nrfutil shell* or my normal settings.

* nrfutil toolchain-manager launch --shell --ncs-version v2.5.0

$ west build  -b circuitdojo_feather_nrf9160_ns
[0/222] Performing build step for 'tfm'
[4/8] Linking C executable bin/tfm_s.axf
Memory region         Used Size  Region Size  %age Used
           FLASH:       31544 B      32256 B     97.79%
             RAM:       18832 B        32 KB     57.47%
[8/8] Generating ../bin/tfm_s.elf
[1/222] Performing build step for 'mcuboot_subimage'
[18/124] Generating zephyr/autogen-pubkey.c
FAILED: zephyr/autogen-pubkey.c
cd .../nrf-sdk-test-2024-02-28/blinky/build/mcuboot && /opt/nordic/ncs/toolchains/20d68df7e5/bin/python3 /opt/nordic/ncs/v2.5.2/bootloader/mcuboot/scripts/imgtool.py getpub -k /opt/nordic/ncs/v2.5.2/bootloader/mcuboot/root-ec-p256.pem > .../nrf-sdk-test-2024-02-28/blinky/build/mcuboot/zephyr/autogen-pubkey.c
Traceback (most recent call last):
  File "/opt/nordic/ncs/v2.5.2/bootloader/mcuboot/scripts/imgtool.py", line 19, in <module>
    from imgtool import main
  File "/opt/nordic/ncs/v2.5.2/bootloader/mcuboot/scripts/imgtool/main.py", line 26, in <module>
    from imgtool import image, imgtool_version
  File "/opt/nordic/ncs/v2.5.2/bootloader/mcuboot/scripts/imgtool/image.py", line 35, in <module>
    from cryptography.hazmat.primitives.kdf.hkdf import HKDF
  File "/Users/me/Library/Python/3.9/lib/python/site-packages/cryptography/hazmat/primitives/kdf/hkdf.py", line 13, in <module>
    from cryptography.hazmat.primitives import constant_time, hashes, hmac
  File "/Users/me/Library/Python/3.9/lib/python/site-packages/cryptography/hazmat/primitives/hmac.py", line 12, in <module>
    from cryptography.hazmat.backends.openssl.hmac import _HMACContext
  File "/Users/me/Library/Python/3.9/lib/python/site-packages/cryptography/hazmat/backends/openssl/__init__.py", line 6, in <module>
    from cryptography.hazmat.backends.openssl.backend import backend
  File "/Users/me/Library/Python/3.9/lib/python/site-packages/cryptography/hazmat/backends/openssl/backend.py", line 63, in <module>
    from cryptography.hazmat.bindings.openssl import binding
  File "/Users/me/Library/Python/3.9/lib/python/site-packages/cryptography/hazmat/bindings/openssl/binding.py", line 14, in <module>
    from cryptography.hazmat.bindings._openssl import ffi, lib
ImportError: dlopen(/Users/me/Library/Python/3.9/lib/python/site-packages/_cffi_backend.cpython-39-darwin.so, 0x0002): tried: '/Users/me/Library/Python/3.9/lib/python/site-packages/_cffi_backend.cpython-39-darwin.so' (mach-o file, but is an incompatible architecture (have 'arm64', need 'x86_64')), '/System/Volumes/Preboot/Cryptexes/OS/Users/me/Library/Python/3.9/lib/python/site-packages/_cffi_backend.cpython-39-darwin.so' (no such file), '/Users/me/Library/Python/3.9/lib/python/site-packages/_cffi_backend.cpython-39-darwin.so' (mach-o file, but is an incompatible architecture (have 'arm64', need 'x86_64'))
[29/124] Building C object zephyr/CMakeFiles/zephyr.dir/lib/os/cbprintf_nano.c.obj
ninja: build stopped: subcommand failed.
[2/222] Performing install step for 'tfm'
-- Install configuration: "RelWithDebInfo"
[36/222] Building C object modules/nrf/subsys/nrf_security/src/CMakeFiles/mbedcrypto.dir/opt/nordic/ncs/v2.5.2/modules/crypto/mbedtls/library/gcm.c.obj
FAILED: modules/mcuboot/mcuboot_subimage-prefix/src/mcuboot_subimage-stamp/mcuboot_subimage-build mcuboot/zephyr/zephyr.hex mcuboot/zephyr/zephyr.elf
cd .../nrf-sdk-test-2024-02-28/blinky/build/mcuboot && /opt/nordic/ncs/toolchains/20d68df7e5/Cellar/cmake/3.20.5/bin/cmake --build . --
[48/222] Building C object modules/nrf/subsys/nrf_security/src/CMakeFiles/mbedcrypto.dir/opt/nordic/ncs/v2.5.2/modules/crypto/mbedtls/library/gcm.c.obj
ninja: build stopped: subcommand failed.
FATAL ERROR: command exited with status 1: /opt/nordic/ncs/toolchains/20d68df7e5/bin/cmake --build .../nrf-sdk-test-2024-02-28/blinky/build
$

The provided Python is x86_64, my system is aarch64.

As you can see, the build system uses its own Python, but links to my system files.

The provided toolchain Python should use its own site-packges.

This is a clean install of v2.5.2 from nRF Connect Desktop.

Thanks in advance,
- Mikael