With painted ceramic, I might go with a mix like 2 tablespoons of bleach in ten gallons of water. This is a stronger mix than drinking water by a fair amount but less than might be used in a load of clothes.
My thinking is that you are not likely to be dealing with anything needing real power to kill if the items are currently dry long enough to kill snail eggs, etc. If you might have snails still alive, a stronger mix might be needed to cut through the shells.
But I do congratulate you for wanting to be safe. I always treat any used equipment I get as I once bought a tank and found they had oil cans stored in them! I clean my plate before I eat even when it might be clean, so I do much the same for my fish. It just cuts the number of wild card problems that might show up later.
Since bleach is so cheap and effective, I just never look further as there is no cheaper, easier, safer way to get the job done. Just cheap $1-2 bleach from the store as long as it has no smells ,etc. added that might throw in things we don't need. Vinegar is a light acid and does some cleaning but it is made by fermenting so I suspect it doesn't do much for killing bacteria as bacteria is what does the process.