Thank you everyone for your replies! I really appreciate them.
Joseph, if you see this, would you mind clarifying something for me--it seems that you're focusing on actual vinegar/acetic acid concentration of the kombucha as the critical factor for safety, versus just the pH--so even if the kombucha was at a sufficiently acidic pH, that wouldn't necessarily make it safe for canning? I ask because kombucha of a pH of ~2.4 or so, comparable to distilled white vinegar, is achievable, but it seems that a similar concentration of acetic acid as white vinegar is not, and it is the pH I have always heard discussed with regard to canning. Also, I can more easily test the pH at home with strips than test the acetic acid concentration via titration. In the meantime, based on what you've said, I think I'll refrain from using the kombucha for canning, although I believe I will try making some refrigerator pickles or pickled eggs (which stay refrigerated) in it just to test the flavor, since those will not be pickling long
enough to go bad and will remain refrigerated the whole time.
As for making fermented pickles as some of you suggested, I already do that as I mentioned, but we prefer the taste and texture of vinegar pickles when it comes to sandwich rounds and spears (whole baby cucumbers are delicious as fermented brine pickles, however). I do fermented pickles of all sorts (not just cucumbers) as well as sauerkraut in crocks.
I also ferment quite often in mason jars with airlocks. They are convenient for small quantities and experimental combinations, they cut down on mold, and they are less messy. I'm including some pictures so y'all can see the set up. The first is of all the parts needed: the flip cap; the airlock; the rubber stopper; a weight to keep your vegetables from floating up to the top (again, cuts down on mold if you keep them submerged)--you can also use a rock (boil it to sanitize) or any heavy thing that will fit in the jar; and the mason jar itself. The second is of the whole system put together (minus the water in the airlock and the contents of the jar). The third is of a jar of fermented carrot-ginger pickles that I had sitting around. You can see that once the airlock and stopper are removed, you can just close the flip cap and stick it in the fridge (to prevent it from fermenting further) or on the shelf. The disadvantage is that it uses a lot of plastic; although the plastic doesn't touch the food, it is far less
sustainable equipment than pottery crocks.
The procedure is simple: Chop/slice up your produce and put it in the jar, leaving a couple inches of headroom. Mix up your brine (varies depending on what you're pickling; 1 Tbsp. salt to one cup water makes a pretty strong brine; you can also re-use brine from previous ferments as a starter, in which case you can make up the difference with a somewhat less salty brine). Pour the brine over the veg and use the weight to trap all the pieces below the brine; remove any that escape or tuck them under. Make sure you have at least an inch of brine over the top of the vegetables. Put water in the airlock, put the airlock in the stopper, put the stopper in the cap, and put the cap on the jar. Put the jar in a dark place where it can remain undisturbed for a while. Leave it for anywhere from a week to a few months, depending on taste and whether you used a starter (you will get a better idea of how long of a ferment you like once you've done a few batches). Stick it in the fridge to stall the fermentation if you want to keep it at a certain level of flavor.
You can also use techniques that use mashing, massaging, or other techniques to take advantage of the vegetables' own juices (such as is traditional for sauerkraut) rather than just pouring brine over them.