Hi, I’m using an IPhone 7 Plus, that being said I  don’t understand how older operating systems becoming incompatible with Ebay has anything to do with using Ebay on the safari browser, the app no longer being compatible I can understand due to security stuff. But Safari is a browser and from what I’ve looked up online, Safari is exactly the same on more modern IPhone models too so I can’t see any good reason for Ebay to not work on older devices via the browser.