This simply isn't true. I'm surprised every comment is stating it can not be done, ever. I have done it for years this way when using a PC. There are a few different methods and i'm not getting in to the details as i'll be here all day.
Method 1) Require a full fresh install. You can customize the installation process of any windows with the right software. You are able to adjust registry settings so the initial install will place all program files to what ever path you choose. When doing this process, it changes all registry edits at time of install to ensure everything works properly. This process you'll be able to customize driver installation, all current windows updates, any programs you wish, the product key and activation, bookmarks and custom web features, remove unwanted programs, custom wallpapers/lock-screen, log-in credentials and so much more. You can have it install from a USB drive where you just boot up, enter the setup drive, and walk away. Come back a couple hours later and your PC is set up 100% the way you need it.
Method 2) Much riskier and should be an expert level in windows installation/registry edits. You can Regedit your way through this process. It's time consuming, due to all the double/triple/quadruple checks on each program installed and all necessary calls to the C: drive and change to D: drive or what ever. This is really only for those who have a lot of experience in registry editing.
Bottom line is, it can and has been done. I had an MSI gaming laptop a few years back with two m.2 drives, 1-TB HDD, and swapped the DVD drive for a 2-TB HDD. In total was 4-TB available space with just the core of windows on one M.2 drive, program files on the other M.2 drive, and downloads and heavy data files on the two HDD drives. Never did it crash in 2+ years until I switched to a Mac-Book Pro. Recently I've switched back to another MSI gaming laptop and in the process to do this all over again. Steam games are simple to move, along with downloads, photos, videos, documents, and other common folders.
I've been installing Microsoft products back since DOS 3.0. So understanding the basic core scripting helped me see how the software works. I've been installing Linux since 1996 and have been dual booting systems since the same time. Worked on Open Source Android development supporting 7 devices for many years. I didn't go to college for any of this, just learned over the years via YouTube and working with other developers on XDA/Github. Anything can be done with computers, if you know how to work the software.