C design pattern performing a list of actions without blocking?

Embedded C. I have a list of things I want to do, procedurally, mostly READ and WRITE and MODIFY actions, acting on the results of the last statement. They can take up to 2 seconds each, I can’t block.

Each action can have states of COMPLETE and ERROR which has sub-states for reason the error occurred. Or on compete I’ll want to check or modify some data.

Each list of actions is a big switch and to re-enter I keep a list of which step I’m on, a success step++ and I come back in further down the list next time.

Pretty simple, but I’m finding that to not block I’m spending a ton of effort checking states and errors and edges constantly. Over and over.

I would say 80% of my code is just checks and moving the system along. There has to be a better way!

Are there any design patterns for async do thing and come back later for results in a way that efficiently handles some of the exception/edge/handling?

Edit: I know how to use callbacks but don’t really see that as “a solution” as I just need to get back to a different part of the same list for the next thing to do. Maybe it’s would be beneficial to know the backend to how async and await in other languages work?

Edit2: I do have an RTOS for other projects but this specific question, assume no threads/tasks, just bare metal superloop.