The status bar isn't really suited for this. Having info about upgrades, contents, and more right on the screen when looking at a barrel would probably be a lot more helpful.

Would be nice to support WAILA/HWYLA and/or The One Probe for this sort of thing.

Partially implemented this in #72. More specifically, upgrades will be visible when hovering over a barrel with an upgrade-related item. I still want to do more with this and integrate it with (at least one of) the mods you mentioned, so I'm leaving the issue open for now.

HWYLA support was added in 1.1.0. Hopefully this should hold things over for now. I'll make a more specific issue in the future if I want to do more with overlays.