How can i learn data science without laptop

Answer 1

Install pydroid3

Answer 2

Many ways:
way # 1: use desktop
#2: Go to internet cafe
#3: buy raspberry py. It is even cheaper than some smart phones
#4: borrow laptop
#5: plug in keyboard + display to your smartphone
#6: build it yourself from spare parts
#7: you got my point

PS.
PC is PC and will never be replaced by phones.
At least near 10 years