Thank you for reaching out and posting this question!
I understand you're looking to add floating banners to the corner of your storefront. One of the options that I've found is by using a third-party app, like Floating Widgets, which allows you to add unlimited floating images and banners. The app also provides a bunch of features, such as making your banners non-closable, so you can prevent your banners from disappearing. If you need any help with this app, the app developer is always available to assist you - you can reach out to them directly through the contact information found in the Support section of their app's page.
Another option to accomplish this is through custom coding and I was able to find that a service provider for this. HulkApps offers a service, called Shopify Custom Banner Ads, where they can help you create a banner on your storefront. Through custom coding, they can make your banners sticky, so it doesn't disappear and they also offer a variety of banner styles (eg. animated, static, etc.) that you can choose from!
I'd love to know if either of these can be a solution for you. Let me know!