I am sorry. You are right. It is possible. I made it as well ages ago and it’s approved. MAybe nothing for first beginner steps 
Hahaha @Bezzo - do you remember that when you asked me what the .json file is for 
Brush sharing! Gradient Alpha Dowmload - #3 by knacki
Anyway, there are some .json files for brushes somewhere here in forum one can search for.
But it is not a no brainer like Procreate, which is said to be complicate by some users.
P.S. one can count on Holger
Btw. all these links are the result of a really “very easy” 2 min. Google search 