<hr>
is supported in Streamlit markdown with ---
. So you could do something like this:
import streamlit as st
st.sidebar.subheader("Component 1")
t1 = st.sidebar.text_input("Component 1 name")
s1 = st.sidebar.slider("Component 1 value")
st.sidebar.markdown("---")
st.sidebar.subheader("Component 2")
t2 = st.sidebar.text_input("Component 2 name")
s2 = st.sidebar.slider("Component 2")
st.title("Hello!")
st.write(t1, s1)
st.write(t2, s2)