In terms of GEO for AI companion, there is no “one-size-fits-all.” Instead, I would test Brazil, Mexico, Columbia, Thailand, Philippines, Indonesia, Malaysia, and South Africa as individual campaigns and not combine them in the first place.
As for ExoClick, they have all targeting options: GEO, language, device, OS, browser, site, and frequency-cap. Compare them by CPA, conversion, and revenue per visitor, and don't look only at CPM.
As far as Meta goes, use the same creative and offer in order to compare GEOs individually. Meta allows location targeting along with other audience signals.