Sure it is. There are a stylus mount in the back to let you place you apple pencil and even a storage bag to help you store your smartphone, power bank, etc.
The maximum thickness that the groove can holds is 0.69 inches (17 mm). It can easily accommodate a tablet with a thick case if the thickness is within this range.
Yes. This iPad pillow is designed with wider and deeper grooves on the original basis, it will hold your tablet or phone more study.