Tomcat and nginx sizing

I manage an application that is deployed on Tomcat servers, with nginx in front, as a reverse proxy. I need some help for the sizing of thread pools / connection pools / ... I find quite a lot of documentation describing the different parameters (Tomcat executors, nginx workers, keepalive, ...) but not much documentation explaining how to find the right sizing. And I'm not sure that I understand correctly the documentation.

For example, I see in my nginx monitoring graphs that I have around 350 active connections, 30 writing connections and 320 waiting connections. I have about 30 requests per seconds.

I have 200 threads configured on the Tomcat server to handle HTTP processing.

I have 1 worker process on nginx with 1024 worker connections.

From what I understand from the docs, the waiting connections are HTTP1.1 keepalive. But I also understand that nginx only does HTTP1.0 as a proxy. I am a bit puzzled. Are those waiting connections consuming Tomcat threads doing just nothing ?

Do you know of a good resource about sizing Tomcat / nginx (or another reverse proxy, the concepts should be the same).

Thanks for your help!