how to convert an image into a rollover / button in a SS section

You can use this code to Website Tools > Custom CSS

[data-section-id="64b8c4a558bd0623e363bda6"] {
li.list-item {
    position: relative;
}
.list-item-content__button-container {
    position: static;
}
a.list-item-content__button.sqs-block-button-element {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    z-index: 9999;
    color: transparent !important;
    background-color: transparent !important;
    border: none !important;
}
.list-item-content__button-container {
    position: static !important;
transform: unset !important;
}
a.list-item-content__button.sqs-block-button-element:before {
    visibility: hidden;
}
.user-items-list-carousel__slide {
    pointer-events: initial !important;
    user-select: unset !important;
}
.user-items-list-carousel__gutter {
    cursor: pointer;
}
li:hover img {
    filter: grayscale(1);
}}