Systems similar to TI's PRUs
NXP's S12X series of processors has an "XGATE coprocessor to achieve higher performance or emulate peripheral modules"...

https://www.nxp.com/products/processors-and-microcontrollers/additional-processors-and-mcus/8-16-bit-mcus/16-bit-s12-and-s12x-mcus:S12S12X

They (NXP) also have various processors that include eTPUs (Enhanced Time Processor Units)...

https://www.nxp.com/products/processors-and-microcontrollers/power-architecture-processors/mpc5xxx-55xx-32-bit-mcus/ultra-reliable-mpc56xx-32-bit-automotive-and-industrial-microcontrollers-mcus/enhanced-time-processor-unit:eTPU