You don't even need to go to Southern Mexico for that. There's a small enclave town in Phoenix, Arizona, called Guadalupe. It's a Mexican / native community. In the centre of town, there's a public square flanked by two Catholic churches.[1] One is a very traditional Catholic church. The other is a syncretic church which (according to people I knew in the community) mixed in many elements of Yaqui spirituality.

The survival of native spirituality, even within syncretic religion, is always somehow reassuring to me, given how much cultural vandalism occurred during the colonisation of the Americas.

1: https://www.google.com/maps/@33.3690036,-111.9644457,3a,15.4...