Northern Mindanao culture/language resources

my lolo grew up in Kinoguitan on Mindanao passed away almost a decade ago and i’ve been meaning to get more connected to the culture. i would ask my mom but because my lolo assimilated when he came to the US, my mom doesn’t know a lot. im wondering if anyone has resources about the culture and language(s) of Mindanao. Im really interested in learning my about my lolo’s culture