I have a question regarding wudu.

All my life I have washed my face and I have always had certainty thst I have reached all parts of my face. recently I have entertained a doubt whether or not I have been reaching a very small area near my nose. I don’t have certainty either way on this doubt.

Can I ignore the doubt for all past wudhus and assume my past wudhu and salat are valid while being more careful for any wudhus going forward?

Yes, you can ignore that doubt for your past wudhu