Scenario 1:
requires 1 host:
To do any work you need to have an OS with a decent graphical user interface (browsing internet, read emails , operate VMs .....)
So in a dualboot setup you MUST boot into Windows.
Scenario 2:
requires 1 host
If you boot this host into ESXi you cant work with a graphical interface as ESXi has none.
So effectively you cant do anything but learn and experiment with ESXi commandline.
Scenario 3:
requires 2 or more hosts:
Now you would use the host with the better graphical user interface to work with.
You would use the host with the most disk space and memory to run ESXi.?
Conclusion:
If you have only one host available dualboot windows10 / esxi makes no sense.
To learn ESXi commandline operation it is more than enough to run ESXi as a VM inside Workstation.
If you have more than one host it is best to dedicate the hosts that are suitable for ESXi to run ESXi exclusively and use the ones that are Laptop-class or Gaming-class to Windows.
> why Fat32 ?
Because that is the only filesystem that can be used for reading and writing by both ESXi and Windows.
Windows cant write VMFS and only has experimental read support for old VMFS versions.
ESXi cant read NTFS.
With Fat32 you are limited to a filesize max of 2GB - which is not sufficient to exchange virtual machine files.
Fat32 also is to fragile for modern usage habbits.
So effectively you have no good option to exchange files with between your 2 operating systems.
Ulli