Is it possible to use an external SDK or data fetching library like Kitsu with RTK Query/Redux Toolkit?

According to the RTK Query documentation, I can create queries like the following:

export const projectsApi = createApi({
  reducerPath: 'projects',
  baseQuery: fetchBaseQuery({
    baseUrl: "https://some-site.com/api/",
    prepareHeaders: (headers) => {
      headers.set('Authorization', `Bearer ${accessToken}`);

      return headers;
    },
  }),
  tagTypes: ['Project'],
  endpoints: (builder) => ({
    fetchProjects: builder.query<Project[], void>({
      query: () => ({ url: `projects` }),
    }),
  }),
});

The above works as expected. However, if want to use an external library like Kitsu to fetch and transform the data, I get the following error:

Here is my updated code while using with Kitsu:

export const projectsApi = createApi({
  reducerPath: 'projects',
  baseQuery: fetchBaseQuery({
    baseUrl: "https://some-site.com/api/",
  }),
  tagTypes: ['Project'],
  endpoints: (builder) => ({
    fetchProjects: builder.query<Project[], void>({
      query: api.get('projects'),
    }),
  }),
});

Here is the code for the api function:

const kitsu = (accessToken: string) => {
  return new Kitsu({
    baseURL: "https://some-site.com/api/",
    headers: {
      'Content-Type': 'application/json',
      'Authorization': `Bearer ${accessToken}`,
    },
  });
};

const api = kitsu("ey....");

Is it possible to override the baseQuery function of RTK Query/Redux Toolkit with the one that Kitsu or any 3rd party package provides?