I'll try to answer this through sharing some personal experiences. When I applied for a customer service job I had rather obvious blocks and stutters during the interview. The two managers interviewing me noticed, and one of them just straight up asked me about it. He immediately declared his curiosity about the cause (chronic or just nervousness) since he had never seen something like it before and asked me if I thought it would be an issue. I really liked the approach because personally I felt like I didn't have to try to hide it anymore and their willingness to just talk about it showed me that I was not making them uncomfortable (I think a lot of the anxiety comes from the feeling of inconveniencing others). On top of that he indirectly told me it was only an issue for him if it was for me. On an idividual basis, when interacting, keeping your attention on the person and not interrupting or finishing sentences for them can go a long way. If it comes to suggesting ressources to help them, I think I personally would not like that. People have thrown sooo many suggestions at me, not realizing that I went through most of them already trying to get better, so while they only wanted to help they really just ended up annoying me. Here I'd say help if you are asked, and only then. So, basically just being patient and attentive is what I would recommend. That alone can go a long way.