Minimalistic cpu implementation

I am trying to implement a CPU in my project. But I can only find some Motherboards with sockets providing the capability to put a CPU onto. But that is not what I am looking for.
I am looking for a minimalistic, small and cheap solution to make use of a CPU. If it is capable to do some stuff on its own, it will be alright. (->no need to communicate with an arduino or something else)

I would highly appreciate, If you could provide me with some key words I could look up or maybe even with some product names.

Thanks in advance, Lucas

In response to the minimalistic request, STM32 Blue Pill

What kind of "CPU" you are talking about? In case of microcontrollers - the simplest one is something like ATTINY or STM8 aliexpress.com/item/STM8S103F3P6-system-board-STM8S-STM8-development-board-minimum-core-board/32802517941.html