It's hard for me to talk about specific temperatures, because I get more acclimatized as the winter progresses. 20 degrees in November feels much colder than 20 degrees in January.
In my locale, a typical year would rarely have temps below -15 F for more than a day or two. My commute is only 4 miles each way, so I'm not in any grave physical danger when I'm out in the cold. And I do a lot of other outdoor activities during the winter.
I have two basic winter rigs:
1. My regular helmet and glasses, neck gaiter, neoprene face mask, thin windproof beanie under the helmet for my ears.
2. My downhill ski helmet, which has built-in ear muffs, and ski goggles.
In addition, I have a ski jacket with a big hood that can go over my helmet, and lighter stuff for warmer temps.
I really like the idea of that magnetic visor. That's so much simpler than the ski goggles.
For the first time this year, I will have a dedicated winter bike, that I built from an old Schwinn frame. It will have a single speed coaster brake hub, so there will be little or no crap on the bike that I have to deal with while wearing mittens, or that could freeze up.