How would I get a constant DC output voltage from an AC voltage input?

 

Well, a half-wave rectified AC is harder to filter than full-wave rectified AC. What sort of project are you working on this for?

 

I need a unified power source to include a socket, USB connection, and a light switch. I know, it's a lot.

 

Use either/ both larger filter capacitors and regulators on the output.

 

If anyone is still looking on this thread —

Add a 2nd wall box and buy a ready-made wall outlet with USB outlets integrated for one box, and a ready-made lit switch for the other.

If it does fail, it will be much easier to fix down the road.