Garuda and Windows 11 in harmony with the spirit of “Do not dual boot Win/Garuda”

Hello all -
I apologize for the long title.
Very simple here. I usually run Garuda on my x86-64 and Mac on my Mac until Asahi is ready for general users. I need Windows for a couple of classes in which commercial software is used.
Not one to mess around I left Windows 11 on the internal SSD. I installed Garuda on an external USB 3 SSD. Created a /boot/efi partition of 300 MB, 220-some GB root partition and maybe 8GB swap. That’s it. Install finished. Reboot. Windows, of course. Selected external SSD in BIOS to boot first. No dice.
I know I am missing something simple. Anyone know of a manual I can read for this?

Thank you

Did GRUB install successfully to the device? You can use a chroot to re-run grub-install to make sure.

Assuming you've disabled Secure Boot (which you must have done to install to begin with), and your machine supports booting from the enclosure, then there's no good reason it wouldn't work.