Installing Win10 programs on drive D is something I've done quite a few times, since my C drive has only 32 GB - really! Most programs will install in D:\Programs instead of C:\Program Files. Read the install options carefully to change the installation path.
PortableApps offers a good selection of portable versions of programs,which you can install completely on any drive (even a thumb drive).
There are tutorials elsewhere you can search for: "how to move Windows 10 apps" and "how to uninstall Windows apps" - the ones that do not have an "uninstall" option.
If your other drive is an SD card you have extra problems. Dropbox will only put its folder on a fixed drive, no matter how 'fixed' you use it. Macrium Reflect Free will create a backup image on an SD card, but you must copy it to an external USB to restore it.