Nokia were experimenting with using their smartphones as web servers in the mid-2000s. You were able to write blog posts and share photos, and if you logged in to the site you could look up your contacts or download your camera roll. There's an article on this here: https://allaboutsymbian.com/features/item/Previewing_Nokias_... .

Obviously it's all very basic, but with a few years of development and polish (and probably someone besides Nokia copying the idea) I think this would be a compelling product. You could basically have the same feature set as something like iCloud but without the subscription or your files going elsewhere.