I think something along those lines could be pretty promising. I’m not sure it’d be the best fit for Open Phil in particular (given that we generally focus on somewhat larger-scale types of grantmaking), but I know of some other folks active in this space who have expressed an interest in this idea/closely related ideas.
Another thing which I think could potentially be really valuable would be for someone to pull together in one place the most important information regarding the practicalities of applying to these and other universities as an international student (including e.g. information about how likely one is to get admitted to such-and-such a university with such-and-such an academic background, which was mentioned in another comment). My sense from skimming some of the existing resources is that they often aren’t great, although I haven’t tried very hard to look for better ones and it’s possible that something like what I have in mind here already exists—in which case just sharing a pointer to this could be equally valuable.