would be cool if you could add support for the Nether Chest mod.

Hello, usually support for modded containers is added by the mods themselves through a plugin.

@Kir-Antipov Do you want support for ShulkerBoxTooltip previews of nether chests ? Tough the compatibility code would be non-trivial since it requires networking.
Plus I don't really know how previews would work when multichannel mode is enabled...
I could submit a PR to your mod if you want.

Do you want support for ShulkerBoxTooltip previews of nether chests ?

I haven't integrated "Nether Chest" even with my own mod, "Packed Inventory," even though it should be easier for me both in terms of maintenance and implementation, since Packed Inventory has a grossly over-engineered tooltip module with built-in networking support :D

When I have a bit more free time on my hands, I will consider it for sure. However, currently, I'm just a bit overworked. In the meantime, feel free to send folks to my repo, as in this case the compatibility layer should indeed be implemented by the authors of countless container mods, not vice versa!