@piersg: As you can see in the tracker this has not been implemented yet.
Your vote has been taken into account.

I'd like to access this information:
https://registry.opendata.aws/ecmwf-forecasts/
through WinSCP, looking forward to hearing that I can use WinSCP to do this.

I have added this request to the tracker:
Issue 2146 – Anonymous access to S3
You can vote for it there.

Having the --no-sign-request just became a necessity for us to use WinSCP. Is there a tracking number or time line for this enhancement request?

This would be a great option to have for people needing to access public datasets hosted on AWS S3 so that they don't have to create an AWS account prior to using WinSCP to access the public datasets.

WinSCP does not have an equivalent of --no-sign-request (yet).
You are the first one to ask for it :)

I am trying to connect to a public S3 bucket using WinSCP.
AWS S3 allows me to connect using AWS CLI with a --no-sign-request option.
e.g.

However, WinSCP wants me to use an Access key and secret to continue to make the call.
Is there ANY way to configure WinSCP with the --no-sign-request option? In order to use anonymous access in cases where it is allowed?

WinSCP error about a malformed header without access key is attached.
Thanks