My version of Retool/its Slack integration plugin does not include these new API functions yet and only lists files.upload in the drop-down menu when adding a new block to a workflow.
Is there any way to use APIs that are not part of the dropdown list? E.g. a blank "wildcard" one where I can specify the call and all args manually, but still use the resource (it's configured authentication)? That would be great.
Thank you for catching this update on the Slack docs, I can flag this for your engineers to look at for updating the query options so that you and future users will be able to use files.getUploadURLExternal/files.completeUploadExternal by default with Slack Resource Queries.
In the meantime, a workaround as you described for custom API calls would be to use REST API Resource. From here you can specify your exact URL path you want to hit and the methods you want to use.
You should be able to add OAuth 2.0 to the REST API which will trigger an auth flow to validate the user before the route is triggered. Here are some docs on how to set that up!