I had already figured out that I must use bootcamp assistant to install windows 10 on my MacBook Pro 2017 14,1 , otherwise if I just boot into a windows installation USB,it can't get my internal keyboard, touchpad and the PCIe SSD. Does anyone know how to install it without using the assistant?
BootCamp assistant is just a utility to make it easier to install Windows on a Mac.
It packages the Windows installer onto a Thumbdrive and slipstreams the drivers to support Apple hardware into the installation so you don't have any non-working devices during boot. It also presents a nice simple GUI to re-partition your HD/SSD.
If you are comfortable installing the necessary drivers (at least keyboard and trackpad/mouse) into a bootable Windows 10 installer then I say, "Go for it."
But I do Windows support for a living and I don't bother with that and frankly don't know HOW to do that. Honestly you are better off just using BootCamp assistant, it is easy and practically foolproof.