One counter-naming that is used in some subcultures working to undo white privilege, colonized thiking, etc. is to refer to 'majority world' and 'minority world' - where 'majority' and 'minority' refer to the quantity of people.

The materially wealthy nations with a small portion of global population and disproportionate power-over are the 'minority world', and the whole rest of the plant, most of the population and far less of the material wealth and political power-over, is the 'majority world'. It is consistent with global demographics as well. since 'white' people are a relative minority on the planet but have somehow managed to get everyone else called 'minorities'.

A problem with the term 'developing countries' is that it assumes and implies that every country should 'develop' like the industrial nations have - that that is the standard to come "up" to.