Mamyshev oscillators (MOs) demonstrate extraordinarily superior performance compared with fiber laser counterparts. However, the realization of a fully fiberized, monolithic laser system without pulse degradation remains a key challenge. Here we present a high-energy MO using large mode area Yb-doped fiber and fiber-integrable interferometric super-Gaussian spectral filters, that directly generates a nearly diffraction-limited beam with ~9.84 W average power and ~533 nJ pulse energy. By implementing pre-chirp management with anti-resonant hollow-core fiber (AR-HCF), the adverse effects of super-Gaussian filtering on pulse quality are effectively mitigated, enabling pulse compression to 1.23 times the transform limit. Furthermore, AR-HCF is employed to provide negative dispersion to compensate for the positive chirp of output pulses, resulting in ~37 fs de-chirped pulses with ~10 MW peak power. This approach represents a significant step toward the development of monolithic fiber lasers capable of generating and flexible delivery of sub-50-fs pulses with tens of megawatts peak power