The National Center for Home Food Preservation recommends canning sauerkraut too. And Salsas have a big write up page, no fermented salsa has been tested.
https://nchfp.uga.edu/how/can_06/sauerkraut.html
" Fully fermented kraut may be kept tightly covered in the refrigerator for several months or it may be canned as follows:
Hot pack – Bring kraut and liquid slowly to a boil in a large kettle, stirring frequently. Remove from heat and fill jars rather firmly with kraut and juices, leaving 1/2-inch headspace.
Raw pack – Fill jars firmly with kraut and cover with juices, leaving 1/2-inch headspace."
I don't do any of this and have made sauerkraut for years...no problems at all. The sites you quote are overly cautious in their recommendations.
and link to salsa page:
https://nchfp.uga.edu/publications/n...ets/salsa.html
"We only recommend recipes and procedures we know to be safe, and encourage consumers to use tested, science-based home-canning recipes from reliable sources like our website or some equipment or home preserving ingredient manufacturers. Our recommended home canning recipes for salsa, as well as a discussion of how ingredients impact safety, are collected in this publication:
http://www.uga.edu/nchfp/publication...onal_salsa.pdf
The same, but individual recipes with links to background information in some of them:
http://www.uga.edu/nchfp/how/can_salsa.html The most flexible procedure we offer for a home-canned salsa is our Choice Salsa found on this menu."
more at both links.
In other words, it isn't safe to do what you've suggested.