Some of the specials listed under holidays may not technically be about those holidays, but they will have themes that relate to the holidays, and in many cases were released around the times of the holidays. So they may have been intended as specific holiday specials, anyway.
stuff I've seen:
miscellaneous
An American Girl Story
LEGO Star Wars Summer Vacation
Valentine's Day
Valentine's Day episodes
Easter
Easter episodes
Halloween
Halloween episodes
Family Guy: A Little Fright Music
Family Guy: Peter, Peter, Pumpkin Cheater
Halloweek
LEGO Star Wars Terrifying Tales
Muppets Haunted Mansion
Werewolf by Night
Christmas
The Guardians of the Galaxy Holiday Special
Maryellen 1955: Extraordinary christmas
The Shepherd