@jlo70 - I started out with chemo brain 30 years ago. Eventually, I leveled out and could feel confident managing my high pressure job.
Once I developed an autoimmune illness, brain fog really set in - waxing and waning with disease activity.
I’m retired now and I don’t have to feel focused all the time- except when playing tennis! I find it necessary to take a caffeine pill or a cup of strong coffee before getting on the court.
I also do a lot of crossword puzzles.
I have a feeling that CNS stimulants such as Ritalin or Adderall would help too- maybe if I was still working I would have looked into trying it.