Enable Windows 10 developer mode from the command line

c:\> reg add "HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\AppModelUnlock" /t REG_DWORD /f /v "AllowDevelopmentWithoutDevLicense" /d "1"

Reference:
https://docs.microsoft.com/en-us/windows/uwp/get-started/enable-your-device-for-development