Opposite prefix for 'ethno-'

The opposite prefix of ethno- is xeno-.

Xeno-: Relating to a foreigner or foreigners.

Origin: From Greek xenos ‘stranger, foreigner’, (adjective) ‘strange’. (Lexico)

Compare this to:

Ethno-: Ethnic; ethnological.

Origin: From Greek ethnos ‘nation’. (Lexico)

Xenocentrism is the opposite of ethnocentrism, and refers to the belief that another culture is superior to one’s own. (The Greek root word xeno, pronounced “ZEE-no,” means “stranger” or “foreign guest.”) An exchange student who goes home after a semester abroad or a sociologist who returns from the field may find it difficult to associate with the values of their own culture after having experienced what they deem a more upright or nobler way of living. (Link)