iPhone mirroring on Mac--using iMessages

My work blocks Apple services during the work day, so sending iMessages during the day on my Mac doesn't work. I think now that I am updated to Sequioa I will be able to mirror and still use my mac to messages during the workday. However, I am trying it out. What is up with not being able to bring up the emoji keyboard on the iPhone while mirroring? I can open the show emoji keyboard on my Mac but can not find a way other than copy and paste to quickly add emojis as I am typing in mirroring on my iPhone with my Mac keyboard.