QCB (Quiet Custom Barrels) is a small Minecraft data pack and resource pack library that makes it simple to prevent your own barrel-based custom blocks from making the vanilla barrel sounds when opened/closed. It includes a way to add your own checks for what counts as a custom barrel, while being fully compatible with multiple data packs.
This library makes it so only vanilla barrels make opening and closing sounds. By default, if there is an area effect cloud with the tag qcb inside the barrel block, it'll treat it as custom. You can add your own checks for what counts as a vanilla barrel by adding your function in the qcb:check_barrel function tag. This repository contains an example of this, with the function namespace:check_barrel checking for a certain armor stand. When you detect that the barrel is a custom block, set the #temp qcb.dummy score to 0.
Before using, make sure to remove or change the namespace:check_barrel entry in the function tag, so the tag isn't invalidated.
Feel free to put the resource/data pack inside another one.