How do you initialize and update git submodules using github desktop?

I am just starting to learn github desktop.

I have two test repos

https://github.com/jayd1860/apptry2
https://github.com/jayd1860/test2/

In apptry2, I created a test2 submodule pointing to the last commit in the test2 repo (the second URL).

Now I want to use github desktop to a) clone apptry2 and b) to initialize and/or update the test2 submodule in apptry2 (that is, I want to do the equivalent of the git command “git submodule update --init” but from github desktop. I looked everywhere in github desktop but I do not see any way to do part b). Is there a way to init submodules in github desktop? And more broadly is there a way to work with submodules in github desktop?

Any help would be much appreciated.