Found in 1 comment on Hacker News
CPR/Choking/First Aid course is probably close to an hour.

How to change your own oil - probably lots of other money-saving home and auto DIY things...

Speed reading and memory tricks can be a multiplier on learning other skills.

How to use automation tools like Zapier and IFTTT - again, a force multiplier.

You might be interested in this book https://www.amazon.com/First-20-Hours-Learn-Anything/dp/1591... - the author has a youtube video that covers it pretty well in 15 minutes - similar to 4-Hour chef, too