I learned to can by buying a pressure canner and going for it. I am more of a "rebel" canner kind of gal. One of these posts says they say not to can flour or dairy. I've found the dairy to be untrue. I can both butter and ghee to improve the lifespan of butter. Yes, I have a good size freezer that is currently holding about 20 or 30 pounds of butter. I have 1/2 pint jars at room temp canned in '21 and still tasty. I learned this from Homestead Heart on YouTube. There is LOTS of helpful information there, just use your brain and comfort level in deciding what to do.
As you point out there are commercialy canned pasta, pumpkin puree, stews... These are all available to us in the stores, yet TPTB says it's a huge no-no for us. Explore and use your common sense.