@sweeneyc - I also started recently and I found a Youtube video that helped with the hardware and software, to build a touch screen. Since it’s been about a month since you posted this. I don’t know if this is going to be redundant.
I’m not building a smart mirror, but more of a smart dashboard. I have an older 52", which I bought a 55" IR touch frame, all from Amazon. I’m still waiting on the IR frame part, but doing research in the meantime and setting up my MM with the modules and testing. I started around the same time you posted this.
I’m also in the U.S.
Here is the specific title of the video. “Smart Mirror Touchscreen (with Face ID) using Raspberry Pi 4 | Full Tutorial”
I found it very informative. It gave me a starting place.