Paste this into your vscode javascript user snippets. Activate it by typing 'nim+TAB'. It will focus the path part of the import statement first which will cause autocomplete to work on the named import.

javascript.json

{
  "Completeable named import": {
    "prefix": ["nim"],
    "body": ["import { ${2:value} } from \"${1:path}\";$0"],
    "description": "A javascript named import statement that works with autocomplete by making you type the path statement first"
  }
}