Need help regarding Frankfurt transit on H4 visa

I’m traveling one-way from the USA to India on Lufthansa with route ATL → FRA → HYD.
I have:

Valid Indian passport

Valid H4 visa stamping in passport

I will only transit through Frankfurt airport and do NOT intend to leave the international transit area.
Since this is a one-way trip (no return ticket to USA currently), do I need any German/Schengen airport transit visa for Frankfurt?

I called Lufthansa but they said they cannot confirm visa requirements.
Has anyone recently traveled on H4 via Frankfurt to India?

Would appreciate if you can share your experience.
Thank you!