OK, thanks for your input. I already have scripts in build steps implementing this for me, so will probably stick with this in my current project. I might try and document this approach on the wiki or in a blog post at some point.

It just doesn't sound simple enough for my preferences.

Thanks for the response, Mark.

Yes, the UI you describe does sound like quite a lot of work. I'd be happy with a simpler alternative, e.g. where the user can enter the module path themselves in a text box and there was a warning or error reported when the build ran if that module path was not present. I feel this would be fairly easy to implement and would certainly handle my use-case. I consider sparse checkout a disk space optimisation, so the consequences of incorrect configuration are less severe than other submodule parameters.

What do you think about this option?

Thanks for the suggestion.  Unfortunately, it has the same user interface challenges as the proposal to support submodule authentication with different credentials for each submodule.

In both cases, the list of submodules (which may vary by branch) needs to be presented to the user so that the can define the sparse checkout configuration for that submodule.

I don't expect to ever implement this enhancement request due to the complexity it will create in the user experience.