Dual SIM: How to turn off cellular for one line while connecting to the data used on the other line?

I have an eSIM(US number) and physical SIM (EU number) in my phone.

Location: when travelling in Europe

The goal: be able to make and recieve wi-fi calling when out and about by connecting US SIM to the cellularly active EU SIM (without connecting to a wi-fi network outside of my device)

Important Points:

• US SIM has turned off cellular pay per call and international day pass. The goal is to not spend any money on the US SIM while travelling abroud.
• The EU SIM has cellular on and is fully functional with cellular and data.

When the phone is directly connected to a Wi-Fi network this solution works well because it allows me to make and receiv calls using Wi-Fi calling.

HOWEVER

The Actual Question: How do I connect the US SIM to the EU SIM AS THE HOTSPOT. I can easily turn my Personal Hotspot on with the EU SIM and share with other devices, BUT how do I connect my US SIM to the Personal Hotspot!?!?

For clarification: I have the Cellular Data set for EU SIM, which means the EU SIM is used when turning on the Personal Hotspot. However, I need to connect my US SIM to the Personal Hotspot created by the EU SIM (within the same device). How do I do this?

Thank you in advance for all of your help!