Then we just need to make mandatory

        protected GitModuleForm(GitUICommands? commands, bool enablePositionRestore)
            : base(enablePositionRestore)
        {
            if (commands is null && _uiCommands is null)
            {
                // In some cases we may want to initialise a form without a module,
                // e.g. a process dialog that executes a git command which is completely self contained.
            }

For making UICommands mandatory, we would need to switch to IGitUICommands instead of GitUICommands...
and YAGNI.

I wonder what these "some cases"...

Ask your self from 4 years ago ;-)
// e.g. a process dialog that executes a git command which is completely self contained.
This is true for all direct usages of FormStatus and FormProcess.

I do not see why FormStatus and all its descendants need to be a GitModuleForm. They have never used GitUICommands and should never do so except for IServiceProvider.
Even FormRemoteProcess uses its own property, only in order to access the subproperty Module for get & set settings but none of the many GitUICommands features nor UICommandsChanged, etc.
refer to 2fcac30

Though since an IGitUICommands - and thereby IServiceProvider - instance is already provided everywhere and since a refactoring of the grown inheritance chain will be even more difficult,
the anyway recommendable main topic of #11269 should be pursued.
FormStatus -> GitExtensionsDialog -> GitModuleForm -> GitExtensionsForm -> GitExtensionsFormBase (with TryGetUICommands)
I still feel uncomfortable with this overuse of IGitUICommands.

I have tried the naive approach to use the completed IGitUICommands instead of GitUICommands - as a quick first step ... I thought.
It will not work without completing IGitModule, too.
Raise event functions would need to be declared public: db5c181.
Several types would need to be moved to GitUIPluginInterfaces: 796cc11.

So I wait for #11269 and the follow-ups.

For the meantime, I am downcasting IGitUICommands to GitUICommands for calling FormProcess.ShowDialog in RunScriptInternal.