Wireless Joint

I have an idea and was wondering if anyone knows if this would work. I'm currently using the At&tb $20 iPad plan on my M1 Nighthawk with identity crisis of the iPad I own. The speeds seem to be much slower than my Galaxy S21 with the Unlimited Elite plan, so I was thinking of switching the tablet line to another Unlimited Elite phone line using the IMEI of an old phone. I realized that although my S21 is using the physical sim for service, there is also an eSim in the phone with a different IMEI. Could that number work in the Nighthawk if I go with the additional Elite line and a physical sim as long as I never activate the actual esim in the phone?