Hello @bartenderonduty,
Thanks for writing in!
The section background option only allow you to have a solid background color, a background image or insert a background video. Inserting a gradient overlay can only be possible with custom css which targets the upper layer. In your section settings, find the “Customize” tab and insert this element css:
$el .x-bg .x-bg-layer-upper-color {
background: rgb(89,0,135);
background: -moz-linear-gradient(26deg, rgba(89,0,135,0.01) 0%, rgba(87,17,163,1) 0%, rgba(80,64,236,1) 44%, rgba(60,146,225,1) 75%, rgba(44,212,217,1) 100%);
background: -webkit-linear-gradient(26deg, rgba(89,0,135,0.01) 0%, rgba(87,17,163,1) 0%, rgba(80,64,236,1) 44%, rgba(60,146,225,1) 75%, rgba(44,212,217,1) 100%);
background: linear-gradient(26deg, rgba(89,0,135,0.01) 0%, rgba(87,17,163,1) 0%, rgba(80,64,236,1) 44%, rgba(60,146,225,1) 75%, rgba(44,212,217,1) 100%);
filter: progid:DXImageTransform.Microsoft.gradient(startColorstr="#590087",endColorstr="#2cd4d9",GradientType=1);
}

I am using this Gradient Generator here: https://cssgradient.io/
Hope this helps.