Append string & {} to your string unions, and you have a type that allows any string, but autocomplete will also show you some values as suggestions.

How does it work?

If you have a type like type Fruit = "apple" | "pear" | string, the typescript compiler will simplify the type to just string, and no autocomplete suggestions will be given.

The trick is to append a type that we know is equivalent to string, but the typescript compiler does not.