Install and Run Win10 with Bootcamp Externally?

[EchoSierra]

I have a 16" MacBook Pro (Nov 2019, Intel i9, Catalina). I want to install windows 10 with Boot Camp to an external drive connected through Thunderbolt since I don't want to dedicate any space on the onboard SSD. Will I be able to install Windows with Boot Camp to an external drive? Will I have any issues booting with this drive? (I know that I need to enable external booting through Recovery Mode since this Mac has the T2 chip; will I have to do this every time?)

Also, if I decide to get an eGPU for games or video editing, will it work on Windows through Thunderbolt if I have Windows booted from this external drive?

 

[DrEGPU]

You can install Windows to an external drive, but it requires some extra steps. I followed these steps on my Mac Pro (which sees nvme drives in the PCIe slots as external for some reason!): https://eshop.macsales.com/blog/40947-tech-tip-how-to-use-boot-camp-on-an-external-drive/

In the comments sections of that article, "Pedro" rightly points out 2 crucial errors:

"1/During the DiskUtility USB Flash Drive preparation, use GUID partition map, not MBR – Without that your Mac will not allow booting from it.

2/When you create your VM on virtualBox, enable EFI in Settings->System – This will allow the VM to properly recognize the drive and windows to install using EFI."

If you don't follow #2, you can still install but you won't be able to boot (can't bless the drive). My install took a little longer than "normal" way of bootcamp, and I got a few blue screens of death. However, it finally restarted enough times to configure Windows to be stable enough to complete the install process.

 

[Petri Krohn]

You can install Windows to an external drive, but it requires some extra steps.

One option is using WinToUSB to create a bootable drive.

Some users report success in using this method to install Windows on an internal NVMe drive.