interface IInterface {
    Method1: (param1: any) => any;
    Method2: (param2: string[]) => any;
}

const keys = Reflect.ownKeys({} as IInterface);

let obj = {};
for (let key in keys) {
    obj[key] = (...params) => {
        console.log(`Chamou a função ${key}!`);
        return params.length > 0 ? params[0] : false;
    };
}

let obj2: IInterface = obj as IInterface; // Aqui eu teria a instancia de IInterface