Keeping face warm in the winter I regularly use a hat under my helmet and a neck warmer.  This keeps me relatively warm in the winter but leaves a bit to be desired.  What are the best options to keep your face warm?

Some people in NYC particularly those riding electric devices wear full face motor cycle style helmets.  I’ve never tried that but it must keep you warm...
A trick that I found is used by NFL players to keep their face warm :
"A jar of Vaseline is an old trick from veteran players to block out the wind"
source: https://www.espn.com/nfl/story/_/id/14525394/seven-ways-nfl-players-stay-warm-frigid-conditions-nfl


BONUS: If you get too hot with the vaseline on you can use the excess to lubricate your drivetrain.

I think some skiing/snowboard goggles with a clear lense will also help in keeping your face warm.
Something like this:
https://mx-deals.nl/oakley-crossbril-o-frame-jet-black-clear-lens.html?gclid=CjwKCAiAluLvBRASEiwAAbX3GU82TCnNSiATDbKyg5txyfgQ22RLn0RFJsY-fwpcHCIu53Mn8MTdwxoCEVkQAvD_BwE



A balaclava looks like it would keep you warm,

you might draw unwanted attention though.



This might be a more subtle but similar alternative: 


There are even versions of balaclavas which have heating elements inside:

                
            
https://www.thewarmingstore.com/heated-balaclava.html


A full face helmet will definitely also help in keeping you warm, but it's not the most practical solution. I've done a quick search regarding heated motorcycle helmets and could not find much so I assume it will not be needed even in cold conditions.
One comment I found on a forum thread regarding heated motorcycle helmets (to illustrate their effectiveness at keeping your head warm): "Are you serious? Why would you actually need that? A helmet acts like a thermos for your head because of the EPS liner. Keeps you warm in the winter and cool in the summer."
source: https://advrider.com/f/threads/heated-cooled-helmet.639790/

There are heated face shields for full face helmets but I believe their main purpose is to prevent frosting/condensation on the face shield itself, not so much to keep your head warm. They look like this: