regarding eSIM, just think of it like you lose your normal sim card and you need to replace it. but instead of getting another physical sim card, you get an eSIM one. once the line is moved over to eSIM, the old sim card is de-activated and cant be used on other devices.
Pixel 6a combo -
$8 talk text PM plan
$0 4GB eSIM data only plan
$1 voip backup line
$8 talk text PM plan
$0 4GB eSIM data only plan
$1 voip backup line