When you first time adding a workflow to a GitHub repo from a feature branch, if you want to test it before merge to main you must give it push trigger, without that - as you said - it won't appear in the UI.

How do you solve the empty values? when you call them you must provide a default with the value you want, for example: echo "${{ inputs.actions || 'create' }}".

After you finish your tests you can remove the push trigger and merge to main, only when the workflow is in main you can use the workflow_dispatch trigger, and now - even in side branches.

If you don't want to test with push and default values, you can merge it to main and then conitnue test in a feature branch.

Why is like this? I have no idea... but this is how GitHub Actions works...