Real-Time process vs Process Affinity

From my understanding a real-time process means the process will get the CPU as soon as it needs it. The kernel is responsible for this task with its internal scheduling mechanism. On the other hand, Process affinity means the process will get a dedicated CPU to itself and it won't be managed by kernel scheduler. So, if I understand correctly, it's even better than being a real-time process. It's like programming for an Arduino but only with a much faster CPU. Also, to my understanding for process affinity we need at least a dual core CPU, and we must leave at least one CPU for the OS itself. So, with the help of process affinity a program that was written for an Arduino can be ported to a Linux board like Raspberry Pi Zero 2 W (which has a quad-core CPU) and would have all the benefits of a microcontroller only with a faster CPU. Is my understanding correct?