I could not find something in the interwebs, no matter how hard I googled.

This does feel hacky and I guess it is a hack or maybe a bodge, but let’s crack on.
You want to select a known option using Ferrum and nothing else?

begin
  browser.at_css("select[name='SELECTNAME']").focus.click.type("SHOWNOPTIONTEXT").click
rescue => exception
  puts exception
end

You need to know the option you would like to select, but in most cases you do.

I feel sorry for this :D