Cart Drawer by HulkApps: allows you to create a customizable cart drawer that can slide in from the side of the screen. You can customize the layout, colors, and text to match your store’s branding. (highly recommend)
Better Cart by Uplinkly:offers a range of customizable features, including the ability to add product recommendations, cross-sells, and upsells to your cart page.
Cart Convert by Techinfini Solutions: allows you to create a custom cart page with a range of design options, including font, color, and layout. You can also add custom text and images to the cart page.
Custom Fields by SolverCircle: allows you to add custom fields to your cart page, such as a text box for customers to leave a note, or an option to add gift wrapping.
Cart Upsell by Gravity Software: allows you to add upsell and cross-sell offers to your cart page.
Hope these can helps. Let us know if you have any further questions.
It is a very flexible side cart app with gift options, a timer, possibility to set a few conditions for gifts and offers, has discount field and so on.