Refactor signature for launcher

[awaelchli]

What does this PR do?

Follow up to #11643
Addresses review comment by @carmocca

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Did you have fun?

I made sure I had fun coding 🙃

cc @Borda @justusschock @awaelchli @rohitgr7 @kaushikb11 @akihironitta

[rohitgr7]

thanks @awaelchli @carmocca for addressing this :)
sorry, I was OOO last week, and also afk, so couldn't address it there.

[tchaton]

LGTM !