To build a custom PWA frontend for your store, start by using PWA Studio, a tool made for Adobe Commerce development. You can use the Venia theme as a base or make your own design. Connect the frontend to your Adobe Commerce backend using GraphQL to show products and other data. Use React to build and change the look of your site. Add service workers to make your site load faster and work offline. Once done, test your site on phones and computers, then launch it.