Is your feature request related to a real problem or use-case?

See:
https://www.typescriptlang.org/docs/handbook/basic-types.html#object

object is a type that represents the non-primitive type, i.e. anything that is not number, string, boolean, symbol, null, or undefined.

Currently, we have export type Primitive = number | bigint | boolean | string | symbol;. We are missing null and undefined.

The complete list is

string | boolean | number | bigint | symbol | null | undefined

Describe a solution including usage in code example

export type Primitive = number | bigint | boolean | string | symbol | null | undefined;

export const isPrimitive = (val: unknown): val is Primitive => {
  if (val === null || val === undefined) {
    return true;
  }
  switch (typeof val) {
    case 'string':
    case 'symbol':
    case 'number':
    case 'bigint':
    case 'boolean': {
      return true;
    }
    default:
      return false;
  }
};

Who does this impact? Who is this for?

TypeScript users