Sketchbook is a great introductory program to get used to digital drawing. I can use it with my XP-Pen Star G640S Drawing Tablet , it compatible with sndroid 6.0 and above devices ,I can draw on my android tablet with prn pressure ,it’s great .
ipad runs on iPad os while surface runs on windows.
I must say ipad has better drawing experience.
In addition, if your partner has a laptop, you can give her some drawing tablets from wacom, huion and xp-pen. more affordable and has good drawing performance.
pctechtest site have some detailed reviews about them, you can take a look.