The most important books are things like first aid and CPR. Or better yet a class because hands on experience beat books learning.
I love the Gingery books and they are great foundations for a hobby. However even in a end of civilization scenario we only need a small minority who knows that content who can teach the rest - that is at best, but quite likely there won't be enough industrial base to produce the aluminum needed and so you are stuck with useless knowledge. Even your 19th century homesteading tends to assume far more industrial base to make some annoyingly hard things.
Most so called practical skills are either not practical in modern civilization (there is far too much population for us all the be hunter/gathers even if we want to); or they are only practical in context of current times. I've seen how to wire your house for electric lights books from the 1920s - most of the things shown wouldn't pass code today. My house was built in 1970, and there are a lot of things that still work but there is good reason we don't allow that anymore.
Had Self-aid and buddy care when I was in the service, and became qualified and volunteered as an EMT for a while after getting out. I do have a Wilderness Survival First Aid Book on my Kindle, and I'll definitely add it to this list.
I actually had a copy of _The Metal Lathe (Build Your Own Metal Working Shop From Scrap, Volume 2)_ ages ago, and slotting in the full leatherbound edition of all 7 volumes is likewise a good fit.
Trying to focus on intellectual things --- practical skills invites the list becoming an extension of my various interests (note the extant shelves on archery and woodworking) and their various intersections, e.g.,
“The Good Life” by Helen and Scott Nearing has an excellent bibliography/citations section.
How to build stone houses, compost and farm organically, etc. A good primer on homesteading. Contains references to things like 19th century homestead manuals
I've considered adding "The Foxfire" books (which I read when I was much younger) and perhaps a text by Roy Underhill, but as noted elsethread, this is intended as an academic/social list.
What would be more interesting, IMHO, books that Cyrus Smith from The Mysterious Island had memorized.
Just from what I saw on HN, I remember Gingery books on metal workshop from scratch, and some homesteading manual from late 19th century.