Checkout UI extension: deep-link “Join loyalty” to a Customer Account UI extension full page (/account/pages/...)?

We have a Checkout UI extension (Preact, purchase.checkout.* target). When the shopper is not a loyalty member we show “Join Loyalty Program” as an <s-button href="...">.

What we do today: we set href to the store’s generic customer account URL, built from shop.storefrontUrl or https://{myshopifyDomain}{base}/account (see getAccountUrl in our checkout extension). That opens the normal account area, not our extension’s dedicated full page.

We also have a Customer Account UI extension (customer-account.page.render, “My Rewards”) that loads on a URL like …/account/pages/<page-uuid> (Shopify-hosted customer account).

Question: What is the supported way to send someone from checkout straight to that customer account extension page? For example: