How to use multiple execution platforms

I have a project that can be built for either Linux or Windows, without any cross-compilation so Linux and Windows are also the two execution platforms. Since there is remote execution, I wanted to be able to build for Linux from my Windows machine using RE.

To keep this short I created a sample project: https://github.com/facebook/buck2/compare/main...Overhatted:buck2-strip-prefix:multiple_target_platforms
It takes inspiration from the following issue: #487
The project just runs some Linux commands which obviously doesn't make sense to do on Windows but it's just a sample for me to understand the execution platform resolution.

When running "buck2 build --target-platforms root//platforms:linux tests:tests" on Windows, I wanted it to select the Linux execution platform automatically (since it's the only one with the "config//os/constraints:linux" constraint) but it tries to run it on the Windows platform, presumably because it is the first one declared, so I don't think I'm using the constraints correctly.

To reproduce the project above:
1. Initialize the repository by running: `buck2 init --git`, `cd prelude` and then `git reset --hard 3b5706b425a88a8641aad8d8ffcc6cdf441b9db0`.
2. Fill the correct remote execution information in .buckconfig
3. Change the "container-image" value to point to a Windows and a Linux docker image available on the RE, depending on the value of platform_name.

Running the command, "buck2 build --target-platforms root//platforms:linux tests:tests", I wanted the genrule commands to be ran on Linux but instead they are ran on Windows, demonstrated by the error message I receive: 'Failed to start process: exec: "sh": executable file not found in %PATH%'

How can I add constraints to the execution platform so that Buck2 automatically selects the correct execution platform for the selected target platform?