Set Up One-Click Checkout for a D2C Store That Uses Custom Checkout

One-click checkout is not available by default with custom checkout, but you can configure it by adding a component to the Checkout page.

At the top of the page, click and select Setup.
In the Quick Find box, find and select All Sites.
For the site you want to update click Workspaces and select the Administration tile.
Select Login & Registration, and enable these settings.
1. Under Registration Page Configuration, allow customers and partners to self register.
2. Under Universal Registration, allow self-registration and passwordless login using the Universal Registration API.
3. Save your changes, and exit Setup.
Go to the store home page, and select the store from the Store dropdown menu.
Select Website Design, and then click Experience Builder.
From the Pages menu, select Checkout, and then click in the Contact Information section of the page to reveal the properties.
Select Enable passwordless login.
From the Components panel, drag the User Registration component onto the Checkout page.
Registered customers can now use one-click checkout. Customers always have the option to check out as a guest and reenter their information.