https://www.youtube.com/watch?v=ypPRdtjGooc

lit-consumer.ts

const Consumer = (Base: any) =>
  class extends Base {
    requestInstance = (key: any) => {
      const event = new CustomEvent("request-instance", {
          detail: {key} as any,
          bubbles: true,
          cancelable: true,
      });

      this.dispatchEvent(event);

      return event.detail.instance;
    };
  };

lit-provider.ts

const Provider = (Base: any) =>
  class extends Base {
    _instances = new Map();

    constructor() {
      super();

      this.addEventListener("request-instance", (event: CustomEvent) => {
        const key = event.detail.key;
        if (this._instances.has(key)) {
          event.detail.instance = this._instances.get(key);
          event.stopPropagation();
        }
      });
    }

    provideInstance = (key: string, instance: any) => {
      this._instances.set(key, instance);
    };
  };