Hi,

I found some things that would improve accessibility for people that navigate with the keyboard:

1. Make elements focusable:
I think it’s best to use the correct HTMl-tags. For example change “button” divs to button tags, like here:
wpc-fly-cart.php line 1087:
$cart_html .= '<div class="woofc-close hint--left" aria-label="' . esc_attr( self::localization( 'close', esc_html__( 'Close', 'woo-fly-cart' ) ) ) . '"><i class="woofc-icon-icon10"></i></div>';

To remove browser button styling:

.woofc-close {    border: none;    margin: 0;    padding: 0;    width: auto;    overflow: visible;    background: transparent;    line-height: normal;    -webkit-font-smoothing: inherit;    -moz-osx-font-smoothing: inherit;    -webkit-appearance: none;
}

2. Trap focus while the Fly cart is open, so you can’t tab to any controls outside of the pane.

Some demo’s I could find:
https://focus-trap.github.io/focus-trap/ (https://github.com/focus-trap/focus-trap)
https://codepen.io/foxareld/pen/VxNoKm (https://allyjs.io/index.html)

I hope you are willing to make changes to improve the accessibility of the plugin