How to keep US phone number while in Japan

I’ll be getting a Japanese eSIM for data and Japanese phone number. I’ll also have access to wifi at the place I’ll be living in, in Japan.

I wanna use my US phone number for 2FA mostly. I’ll be using other apps like Discord to talk with family. I really want to avoid paying for international usage since I’m already getting a Japanese SIM.

Another thing I’m worried about is AT&T (my US carrier) cancelling my phone plan because I’ve been out of the US for too long. I read that T-Mobile does this, but wasn’t sure about AT&T.

I was thinking of continuing to pay my US phone plan while in Japan. Then getting a Japanese eSIM to use for data, and turning off cellular data for my US SIM. Is this enough to receive texts to my US phone number, or is it necessary to port using Google Voice? What are the steps to ensure my US phone plan doesn’t get cancelled by my carrier, and to keep receiving texts to US phone number while using Japanese SIM cellular data?