On one hand, I would ask why? I always have my phone with me to use as a hotspot and I usually have my cellular iPad. The iPad can last 24 hours as a hotspot (https://www.imore.com/yup-ipad-air-still-gets-24-hours-batte...)

On the other hand, seeing that I always have my phone with me, I don’t need my cellular connection with my iPad either and I could save that $20 a month.

I do wonder if even T-mobile would be as generous with data with a laptop as they would with a tablet.