Fabric connections appear to require a static endpoint

We're migrating Azure Data Factory (ADF) pipelines to Microsoft Fabric Data Factory using the REST API. Many of our ADF linked services are parameterized. For example, an Azure SQL linked service uses a server name like:

@{concat('company-sqlsrv-', linkedService().environment, '-database.database.windows.net')}

where environment is provided at runtime (for example, dev, test, or prod) through a global parameter. We also have REST and ADLS linked services where the endpoint or storage path is supplied dynamically (for example, linkedService().baseUrl or a storage path constructed from runtime parameters such as {layer}/{source}).

Fabric connections appear to require a static endpoint, so these don't seem to map directly.

I have a few questions:

1. Is there a supported way to create a Fabric connection that remains parameterized like an ADF linked service, or is creating one connection per concrete endpoint the only supported approach?

2. For "generic" linked services that are reused with many runtime URLs or storage locations, what is the recommended design pattern in Microsoft Fabric?

3. When calling POST /v1/connections, what is the correct credentialDetails payload for creating an Azure SQL connection through an On-Premises Data Gateway? We're receiving a 400 InvalidInput response with the message:

   "The Values field is required."

   Additionally, WorkspaceIdentity appears to be rejected for gateway-bound connections.

If anyone has documentation, sample payloads, or recommended migration patterns for this scenario, I'd really appreciate the guidance.