If you just want a gradient, see this (while this is for a button the idea is still the same),
Example view with gradient background:
{
"custom": {},
"params": {},
"props": {},
"root": {
"meta": {
"name": "root"
},
"props": {
"style": {
"background-image": "linear-gradient(red, yellow)"
}
},
"type": "ia.container.coord"
}
}