Huachao Mao has made an interesting extension for VSCode: the REST Client.
https://marketplace.visualstudio.com/items?itemName=humao.rest-client
In a separate file with a .http or .rest extension, you can describe your simple requests and submit them without leaving the editor.
There is syntax highlighting, support for GraphQL, multipart/form-data, and specifying files as the request body.
There is no OAuth support.