rustup package unavailable

[Milind Kamble]

Hello,
   I am very very new to rust. Quite a few site related to beginners
level rust instructions mention to use rustup to install some rust
packages.
There is no rustup package in the guix package list. I have installed
rust and rust-cargo.
Specifically, I am trying to setup a build flow for stm32
microcontroller board based on the directions at
https://docs.rust-embedded.org/book/intro/install.html
I am stuck at having to do this step:
sh> rustup target add thumbv7m-none-eabi

Any help about installing rustup in GUIX would be arppreciated

-Milind