In thinking about how non-Christians might be saved without compromising the claim that Jesus is the unique agent of salvation, I wonder if it might be helpful to think about the different ways in which we can be said to know someone. I can know someone in virtue of having met them and engaged in personal interaction with them, or I can know things about someone (e.g. by reading books about them, having them described to me, or under a particular title like “The Queen of England”). This is similar to, though probably not the same as, Bertrand Russell’s distinction between knowledge by acqaintance and knowledge by description.
Applied to the question of salvation, maybe we can say that it’s possible to become acquainted with Jesus and respond to him in an appropriate way, without encountering him under the same description as Christians would use. This could take place in the context of other religions, but might not necessarily have to. Though it would be difficult, if not impossible, to specify exactly which events would count as such encounters, which is why this kind of speculation should not be taken to be a substitute for Christians sharing the gospel.
Just some thoughts – even less well thought out than the usual fare here.