But it is fun to accelerate to M2 at the tropopause, select an unreasonable pitch attitude, then around zero g and enjoy the ride.
Problems include required safety equipment not normally worn eg pressure jerkin, expect engine and aircraft handling issues.
More often done is Vne at dot feet, full thrust and a vertical departure, recovering a very short time later, at zero IAS possibly in a tailslide at around 30 to 40 k feet.
Kinetic energy is king, both manoeurvres are at very low or zero g.
Misspent youth!