Customizing existing blocks with Checkout Extensions

[asmerkin]

I'm working on a store that already has a customized checkout (using the checkout.liquid available for plus stores). We want to move to checkout extensions, but I don't see how to use extensions to modify existing elements from the checkout page, like
- Filling the shipping address based on some info provided in a previous step.
- Moving the discount code input location within the page.
- Reading some trial info and updating some text in the checkout page.

How can these be achieved using checkout extensions?

Thank you.

[momoluca]

Hi did you figure this out? 

[asmerkin · Accepted solution]

Hi @momoluca , it's not supported.

We can't modify Checkout DOM elements using UI extensions since these are built using WebAssembly, and are self-contained.