The render_ helpers returns HTML so they can’t be piped to element, you need to do it step by step like this:
# this will display your component
view
|> element("#menu_opener")
|> render_click()
# you interact with it with the same `view` you mounted earlier
assert
view
|> element("#filter-input")
|> render_change(%{term: "o"}) =~ "oo"
