A simple beacon sample does not build for thingy91. I am attaching relevant files.
* Executing task: nRF Connect: Build: beacon_thingy91/build (active)
Building beacon_thingy91
west build --build-dir c:\ncs\MyApps\beacon_thingy91\build c:\ncs\MyApps\beacon_thingy91
[0/41] Performing build step for 'mcuboot_subimage'
ninja: no work to do.
[1/41] Building C object zephyr/kernel/CMakeFiles/kernel.dir/version.c.obj
[3/39] Building C object zephyr/kernel/CMakeFiles/kernel.dir/sem.c.obj
[4/39] Building C object zephyr/kernel/CMakeFiles/kernel.dir/mailbox.c.obj
[5/39] Building C object zephyr/kernel/CMakeFiles/kernel.dir/stack.c.obj
[6/39] Building C object zephyr/kernel/CMakeFiles/kernel.dir/system_work_q.c.obj
[7/39] Building C object zephyr/kernel/CMakeFiles/kernel.dir/timer.c.obj
[8/39] Building C object zephyr/kernel/CMakeFiles/kernel.dir/xip.c.obj
[9/39] Building C object zephyr/kernel/CMakeFiles/kernel.dir/condvar.c.obj
[10/39] Building C object zephyr/kernel/CMakeFiles/kernel.dir/queue.c.obj
[11/39] Building C object zephyr/kernel/CMakeFiles/kernel.dir/mutex.c.obj
[12/39] Building C object zephyr/kernel/CMakeFiles/kernel.dir/timeout.c.obj
[13/39] Building C object zephyr/kernel/CMakeFiles/kernel.dir/pipes.c.obj
[14/39] Building C object zephyr/kernel/CMakeFiles/kernel.dir/mempool.c.obj
[15/39] Building C object zephyr/drivers/bluetooth/CMakeFiles/drivers__bluetooth.dir/hci/h4.c.obj
FAILED: zephyr/drivers/bluetooth/CMakeFiles/drivers__bluetooth.dir/hci/h4.c.obj
C:\ncs\toolchains\v2.1.0\opt\zephyr-sdk\arm-zephyr-eabi\bin\arm-zephyr-eabi-gcc.exe -DKERNEL -DNRF52840_XXAA -DUSE_PARTITION_MANAGER=1 -D_FORTIFY_SOURCE=2 -D__PROGRAM_START -D__ZEPHYR_SUPERVISOR__ -D__ZEPHYR__=1 -IC:/ncs/v2.1.0/zephyr/subsys/bluetooth -IC:/ncs/v2.1.0/zephyr/include/zephyr -IC:/ncs/v2.1.0/zephyr/include -Izephyr/include/generated -IC:/ncs/v2.1.0/zephyr/soc/arm/nordic_nrf/nrf52 -IC:/ncs/v2.1.0/zephyr/soc/arm/nordic_nrf/common/. -IC:/ncs/v2.1.0/nrf/include -IC:/ncs/v2.1.0/modules/hal/cmsis/CMSIS/Core/Include -IC:/ncs/v2.1.0/modules/hal/nordic/nrfx -IC:/ncs/v2.1.0/modules/hal/nordic/nrfx/drivers/include -IC:/ncs/v2.1.0/modules/hal/nordic/nrfx/mdk -IC:/ncs/v2.1.0/zephyr/modules/hal_nordic/nrfx/. -IC:/ncs/v2.1.0/modules/debug/segger/SEGGER -IC:/ncs/v2.1.0/modules/debug/segger/Config -IC:/ncs/v2.1.0/zephyr/modules/segger/. -IC:/ncs/v2.1.0/modules/crypto/tinycrypt/lib/include -IC:/ncs/v2.1.0/nrfxlib/softdevice_controller/include -isystem C:/ncs/v2.1.0/zephyr/lib/libc/minimal/include -isystem c:/ncs/toolchains/v2.1.0/opt/zephyr-sdk/arm-zephyr-eabi/bin/../lib/gcc/arm-zephyr-eabi/10.3.0/include -isystem c:/ncs/toolchains/v2.1.0/opt/zephyr-sdk/arm-zephyr-eabi/bin/../lib/gcc/arm-zephyr-eabi/10.3.0/include-fixed -isystem C:/ncs/v2.1.0/nrfxlib/crypto/nrf_cc310_platform/include -Os -imacros C:/ncs/MyApps/beacon_thingy91/build/zephyr/include/generated/autoconf.h -ffreestanding -fno-common -g -gdwarf-4 -fdiagnostics-color=always -mcpu=cortex-m4 -mthumb -mabi=aapcs -mfp16-format=ieee --sysroot=C:/ncs/toolchains/v2.1.0/opt/zephyr-sdk/arm-zephyr-eabi/arm-zephyr-eabi -imacros C:/ncs/v2.1.0/zephyr/include/zephyr/toolchain/zephyr_stdint.h -Wall -Wformat -Wformat-security -Wno-format-zero-length -Wno-main -Wno-pointer-sign -Wpointer-arith -Wexpansion-to-defined -Wno-unused-but-set-variable -Werror=implicit-int -fno-asynchronous-unwind-tables -fno-pie -fno-pic -fno-reorder-functions -fno-defer-pop -fmacro-prefix-map=C:/ncs/MyApps/beacon_thingy91=CMAKE_SOURCE_DIR -fmacro-prefix-map=C:/ncs/v2.1.0/zephyr=ZEPHYR_BASE -fmacro-prefix-map=C:/ncs/v2.1.0=WEST_TOPDIR -ffunction-sections -fdata-sections -std=c99 -nostdinc -MD -MT zephyr/drivers/bluetooth/CMakeFiles/drivers__bluetooth.dir/hci/h4.c.obj -MF zephyr\drivers\bluetooth\CMakeFiles\drivers__bluetooth.dir\hci\h4.c.obj.d -o zephyr/drivers/bluetooth/CMakeFiles/drivers__bluetooth.dir/hci/h4.c.obj -c C:/ncs/v2.1.0/zephyr/drivers/bluetooth/hci/h4.c
In file included from C:\ncs\v2.1.0\zephyr\include\zephyr\toolchain\gcc.h:88,
from C:\ncs\v2.1.0\zephyr\include\zephyr\toolchain.h:50,
from C:\ncs\v2.1.0\zephyr\include\zephyr\sys\errno_private.h:10,
from C:\ncs\v2.1.0\zephyr\lib\libc\minimal\include\errno.h:32,
from C:\ncs\v2.1.0\zephyr\drivers\bluetooth\hci\h4.c:9:
C:/ncs/v2.1.0/zephyr/drivers/bluetooth/hci/h4.c: In function 'bt_uart_init':
C:\ncs\v2.1.0\zephyr\include\zephyr\device.h:96:39: error: '__device_dts_ord_DT_CHOSEN_zephyr_bt_uart_ORD' undeclared (first use in this function)
96 | #define DEVICE_NAME_GET(name) _CONCAT(__device_, name)
| ^~~~~~~~~
C:\ncs\v2.1.0\zephyr\include\zephyr\device.h:276:37: note: in expansion of macro 'DEVICE_NAME_GET'
276 | #define DEVICE_DT_NAME_GET(node_id) DEVICE_NAME_GET(Z_DEVICE_DT_DEV_NAME(node_id))
| ^~~~~~~~~~~~~~~
C:\ncs\v2.1.0\zephyr\include\zephyr\device.h:296:34: note: in expansion of macro 'DEVICE_DT_NAME_GET'
296 | #define DEVICE_DT_GET(node_id) (&DEVICE_DT_NAME_GET(node_id))
| ^~~~~~~~~~~~~~~~~~
C:\ncs\v2.1.0\zephyr\drivers\bluetooth\hci\h4.c:561:11: note: in expansion of macro 'DEVICE_DT_GET'
561 | h4_dev = DEVICE_DT_GET(DT_CHOSEN(zephyr_bt_uart));
| ^~~~~~~~~~~~~
C:\ncs\v2.1.0\zephyr\include\zephyr\device.h:96:39: note: each undeclared identifier is reported only once for each function it appears in
96 | #define DEVICE_NAME_GET(name) _CONCAT(__device_, name)
| ^~~~~~~~~
C:\ncs\v2.1.0\zephyr\include\zephyr\device.h:276:37: note: in expansion of macro 'DEVICE_NAME_GET'
276 | #define DEVICE_DT_NAME_GET(node_id) DEVICE_NAME_GET(Z_DEVICE_DT_DEV_NAME(node_id))
| ^~~~~~~~~~~~~~~
C:\ncs\v2.1.0\zephyr\include\zephyr\device.h:296:34: note: in expansion of macro 'DEVICE_DT_NAME_GET'
296 | #define DEVICE_DT_GET(node_id) (&DEVICE_DT_NAME_GET(node_id))
| ^~~~~~~~~~~~~~~~~~
C:\ncs\v2.1.0\zephyr\drivers\bluetooth\hci\h4.c:561:11: note: in expansion of macro 'DEVICE_DT_GET'
561 | h4_dev = DEVICE_DT_GET(DT_CHOSEN(zephyr_bt_uart));
| ^~~~~~~~~~~~~
[16/39] Building C object zephyr/kernel/CMakeFiles/kernel.dir/work.c.obj
[17/39] Building C object zephyr/kernel/CMakeFiles/kernel.dir/poll.c.obj
[18/39] Building C object zephyr/kernel/CMakeFiles/kernel.dir/sched.c.obj
ninja: build stopped: subcommand failed.
FATAL ERROR: command exited with status 1: 'c:\ncs\toolchains\v2.1.0\opt\bin\cmake.EXE' --build 'c:\ncs\MyApps\beacon_thingy91\build'
* The terminal process terminated with exit code: 1.
* Terminal will be reused by tasks, press any key to close it.
