How am I meant to edit/upload/modify ~/.aws/credentials in GrafanaCloud? I can’t find a place to upload this.
you can’t, you have to specify the client id and secret instead.
My account needs to Assume a Role and the only way to Assume a Role with Grafana in GrafanaCloud is to use the credentials file.
Does this mean I cannot use this Grafana functionality? Or will it be changed to allow me to specify the Role to assume alongside the credentials?
No this is not correct , the only way to use Assume role is if you use have given EC2 machine running grafana a specific role the can be assumed. Or that is how I think it works. That is Assume Role only works if you run grafana on EC2. The Assume Role option is not available if you auth via credentials file or secret/clientId.
The only auth option available on GrafanaCloud is specifying secret & client id