Magento 2 One Step Checkout Extension :
https://www.magetop.com/magento-2-one-step-checkout-extension.html
Magento 2 One Step Checkout and Layouts will allow users to complete the checkout process without spending time moving to a separate page for payment. Above all it compliments all the features of cart page into checkout page like user can change quantity and remove products at same page using ajax.
One Step Checkout For Magento 2 Features :
- Optimized Checkout page.
- Supports nearly 100% Payment, Shipping methods.
- Compatible out-of-the-box with the 3rd-party modules.
- Allows/Supports Gift Wrap, Gift Message.
- Allows/supports leaving comments and setting delivery time.
- 100% Open-source, Support multi-store, Support multi-language.
- Easy to install and customize.
- And many more Features ...