Unfiltered apple juice can be a remedy for gallbladder pain.

People also do gallbladder flushes with Epsom salt, olive oil, and grapefruit juice (the instructions and recipes are online).

Digestive bitters, dandelion, and milk thistle can help support the whole biliary tract, so there's less stress on the gallbladder itself.

People use the herb chanca piedra for gallstones, though it's usually used for kidney stones.

When I was having gallbladder issues, I learned about three yoga poses that help with gallstones, and for me they provided relief. I suppose it makes sense because they provide mechanical help in moving along sludge and stones. The poses are bow, cobra, and locust.