I am not entirely sold on keeping the *I* out of the conversation, though I do recognize that you started the conversation with that parameter, Asa, so if you'd rather call that a given, I can let it go. But my go-tos are "I am here." "I hear you." "I see you." And I also use reflective listening extensively, too, repeating back what the person has said in slightly different words to show that I heard and understood what they said, and also because I find it so helpful to offer the opportunity for them to take in their own output and hear it in a different voice. There may be better ways of explaining that, but it feels like something I can do that is helpful, confirms that I am present and connected, and affirms their feelings and/or position.
I believe that a significant amount of what people need is to be seen, heard, and affirmed. If I cannot connect with exactly what they are telling me, I can connect with their need to feel connected, for example. It is still about them. I'm not hijacking (as I might be if I switched the conversation to a story about myself, or a description of how I feel, or some explanation of why I can relate.)
I am present. I am here. I hear you. I see you. I am listening. I appreciate your words, your trust in me, your perspective, how challenging this is for you, how frustrating this situation is for you, how overwhelming this is for you. I am with you and I can look you in the eye and I can handle what you are sharing with me and I believe in your ability to get through this difficult time.
And so on.