Currently playing a 1.19.2 pack (using sophisticatedstorage-1.19.2-0.9.7.765.jar), so if this has already already been made for a newer version, then great.

Would be nice with an upgrade that could make a barrel/chest output a redstone signal as if a comparator was placed beside it.
Would the cool if the advanced version could set the fill ratio before outputing redstone, i.e a slider that decides what is classified as 0 for the comparator output. Maybe the advanced version could also allow toggeling between it outputting a weak or strong signal.

With this suggested upgrade, the player could create a more compact system that reacts to the fullness of a barrel/chest inventory.

Not entirely sure how this upgrade would act if multiple is added, if that needs to be a consideration.

Hold on - have you tried placing comparator next to a storage and see how it reacts to different fill levels?

I know that i can place a comparator beside it, but that needs supports for the redstone, and can quickly become a large build if you have many barrels/chest what need to all be read and effect some other block.

Currently trying to automate Auto Trader, with barrels as the output buffer, using hopper upgrades, and controllers to route items to central storage.

Going to use Integrated dynamic to shut off my Modular routers once the barrels are filled to a certain %, depending on what i am buying.

If a comparator upgrade existed as suggested, that could emit a strong signal, then i would not need to do any additional logic.
If i where to add comparators to these barrels then i'd need to move the build around abit, to stay within the confines of my (9x9) areas that i want to keep builds to.

As i write the above, i did consider the use of a redstone torch for moving the signal up 1 block, and then just setting the Modular router to run with redstone signal. This would increase the tile size from 2x2x1 to 2x3x1.

Another reason for this suggestion is that Funtional Drawers has a similar upgrade too, so i don't see why this couldn't have it too.