Being a bit of an asperger’s case, I have developed over the years a practice of listening to people talk and at the same time try to process in my head the mood of the speaker, because sometimes I'm not able to do it instinctively. I am getting better with practice though.

Sometimes I respond to my interlocutor by naming the emotion they're expressing, not necessarily directly ("oh you're angry!?") but rather stuff like "oh it must be infuriating what happened!"

I find people do respond positively to that, and that it opens a deeper connection.

There's the practice of Non Violent Communication [1], which has inspired me, though I'm not a zealous follower of the technique. It can seem condescending at the hands of the wrong person.

[1] https://en.m.wikipedia.org/wiki/Nonviolent_Communication

Edit: to me this is not about validation. It's about being more attuned to what the other person's going through. It's about empathy and compassion.