Does the expiation suffice for making up for many years of missed Ramadan days, given that they were missed due to ignorance and the inability to make them up due to chronic migraine?

All missed days from Ramadan (definition), whether few or many, must be made up, even if years have passed, based on the Almighty's saying: ﴿then a [corresponding] number of other days﴾. In addition to making up the fast, one must also give a mudd of food to a needy person for each day missed, if there was a delay in making up the fast until the next Ramadan began without a valid excuse. This is based on what has been reported from the Maliki, Shafi'i, and Hanbali schools of thought.