MAC OS
In order to install Mac OS on a windows machine with VirtualBox - you need to obtain the .ISO file for macOS and mount is as optical drive.
There are some extra steps required, to avoid being stuck on the language screen or have a boot-loop.
El capitain seems to work - Sequoia doesn't seem to work for me.
in VirtualBox, use your intuitive steps to set up an MacOS image, and link the iso with an optical device
Also, enable USB3.0 else - your input devices will not be captured (like mouse and keyboard)
Then, execute thi scommand in a commandline, to fix the bootloop
cd "%programfiles%\Oracle\VirtualBox\"
VBoxManage.exe modifyvm "YouMacImageName" --cpuid-set 00000001 000106e5 00100800 0098e3fd bfebfbff
VBoxManage setextradata "YouMacImageName" "VBoxInternal/Devices/efi/0/Config/DmiSystemProduct" "MacBookPro15,1"
VBoxManage setextradata "YouMacImageName" "VBoxInternal/Devices/efi/0/Config/DmiSystemVersion" "1.0"
VBoxManage setextradata "YouMacImageName" "VBoxInternal/Devices/efi/0/Config/DmiBoardProduct" "Mac-551B86E5744E2388"
VBoxManage setextradata "YouMacImageName" "VBoxInternal/Devices/smc/0/Config/DeviceKey" "ourhardworkbythesewordsguardedpleasedontsteal(c)AppleComputerInc"
VBoxManage setextradata "YouMacImageName" "VBoxInternal/Devices/smc/0/Config/GetKeyFromRealSMC" 1
VBoxManage setextradata "YouMacImageName" "VBoxInternal/TM/TSCMode" "RealTSCOffset"