Higher-order soliton dynamics, specifically soliton compression and fission, underpin crucial applications in ultrafast optics, sensing, communications, and signal processing. Bragg solitons exploit the strong dispersive properties of periodic media near the photonic band edge, enabling soliton dynamics to occur on chip-scale propagation distances and opening avenues to harness soliton compression and fission in integrated photonic platforms. However, implementation in CMOS-compatible platforms has been hindered by the strong nonlinear loss that dominates the propagation of high-intensity pulses in silicon and the low-optical nonlinearity of traditional silicon nitride. Here, we present CMOS-compatible, on-chip Bragg solitons, with the largest soliton-effect pulse compression to date with a factor of x5.7, along with the first time-resolved measurements of soliton fission on a CMOS-compatible platform. These observations were enabled by the combination of unique cladding-modulated Bragg grating design, the high nonlinearity and negligible nonlinear loss of compositionally engineered ultra-silicon-rich nitride (USRN: Si7N3).