I am currently running my app locally and try to use emojis by shortcodes within st.selectbox. but it just appears as a text.
You cannot use shortcodes in the options, but you can include the emoji as text.
options = ["😎", ":sunglasses:"]
st.selectbox("Select", options=options)
PS If you want shortcodes supported in options, here’s a GitHub feature request for you to upvote. It covers full Markdown support. Allow markdown options elements for selectbox widget · Issue #7466 · streamlit/streamlit · GitHub