Tools for the decisions, not just the files
Most website-to-APK tools only generate assets. These are built around the questions that actually come up when you convert a site: is it ready? what should the APK be called? what will the status bar look like? which permissions does it honestly need? what happens when the connection drops? will Play accept the listing? Each tool answers one of them in the browser and hands you the output — a score, an icon set, a block of manifest XML, an HTML file — to use in the APK builder or in a native Android project.
None of them uploads anything. Icons are drawn on a canvas, previews are rendered locally, checks run on the text you type. They work offline once loaded, and nothing you enter is stored or sent.
If you would rather skip the pieces, the builder takes a website URL and returns a signed APK in a few minutes, generating the icon set, the theme and the manifest for you. These tools are for seeing the pieces first — and for the details the converter cannot decide on your behalf.