The Americanized holiday may be something completely different, but the energies and astronomical significance is always still there no matter what is put over the top. Its like those churches being built over sacred sites, still the same energy on the underlying part.
Bro OMO gave a lot of good information on that aspect, and I have already been told that this is the day when the veil between the two worlds is at its thinnest. So I am connecting the Day of the Dead with Halloween because the day it falls on which is October 31st, if it fell on November 1st I would say the same thing. Still days when those worlds are coming together.
Even in your research about the ancient Druids doing magickal things on this day, from what I know the real ancient Druids and Celts were colored people. I wonder where the Druids got this practice from? Maybe AFRICA. I could be wrong. I'll be turning on my music and dancing with my deceased fam.
I will be out with my Aunt and her daughters and Grandkids, chilling in Inglewood then probably visit some Family gravesites at Rose Hills and Inglewood mortuary, burn some incense, have a smoke and clean some headstones. Then go up to Bakersfield the next weekend and do the same at a family site in a small town named Shafter where my Dad lays between his parents and the Elders who made the trek to Cali from Alabama, Texas, Oklahoma and New Mexico. Then go over my aunt's and eat some gumbo and fried fish, in a smaller town named Wasco.