I think animal diplomacy has lots of chance at the level of individual national parks or local governments.
Zoos which sponsor reserves for years and put sizable money into it could be rewarded with local animals as a gift. This could also sensibly start an insurance population ex-situ. I am surprised it is not done.
For example, Bale Mountains reserve in Ethiopia has most of infrastructure sponsored by the Frankfurt Zoological Society and other foreign donors. This place would collapse without foreign support. So I am surprised that Western zoos received a big nyet when they wanted to import animals from the region. This is an example, but many tropical reserves and animals are in the same situation. Another matter is that Western zoos currently have little interest in importing new species.