bcdedit - Dynamically dual-boot Windows and Linux

Question

For the last couple of days I am searching for an answer, but I constantly run into brick walls.

I want to create a bootable USB with a custom Linux-based OS (for the sake of this conversation, let's just say it is Ubuntu) which I could boot into from Windows in a user-friendly fashion.

Host operating system is Windows 10.

I want to accomplish the following:

1. User inserts the USB stick with the custom OS.
2. A simple GUI opens with a Launch button.
3. When Launch is clicked, it should modify boot configuration to boot from USB and reboot.
4. Windows Boot Manager should delegate delegate booting to the Linux bootloader and open Live browse for the custom OS (bootloader and GUI will be something like Ubuntu's)
5. After reboot, it should return to the default OS (Win 10) without any trace, so the boot order would be one time only.

I have tried messing with BCDEdit, but with no luck, also I have tried using EasyBCD and Visual BCD, but I could not create a working BCD entry which would start the booting process from my USB.

Also, it seems like BCDEdit is poorly documented by Microsoft, and all other use cases I found online do not cover my case.

Also it is very important that the end-users do not have to do any setup, changing boot configuration should be done programatically.

I would appreciate any idea how to create a BCD entry which would chainload Linux bootloader from USB drive.