Other mods hoppers can't input items into Quark Oddities Item Pipes.
Hoppers tested:

• BitHop BitHop -> crashes
• BitHop FluxHop -> doesn't work
• BitHop PullHop -> doesn't work
• BitHop ScrewHop -> doesn't work
• Hopper Ducts Grated Hopper -> works
• Hopper Ducts Hopper Duct -> works
• Immersive Engineering Conveyor Belt -> doesn't work
• Immersive Engineering Dropping Conveyor Belt -> doesn't work
• Immersive Engineering Item Router -> doesn't work
• Inspirations Pipe -> doesn't work
• Mob Grinding Utils Absorption Hopper -> works
• Refined Relocation Fast Hopper -> doesn't work
• Refined Relocation Filtered Hopper -> doesn't work
• Uppers Upper -> works

I only looked at the code briefly, but it appears AutoRegLib's TileSimpleInventory does not return a CapabilityItemHandler from hasCapability. I can vouch for Inspirations specifically I opted to have the pipes only support inventories with CapabilityItemHandler at this time, since all inventories should be using the Capability anyways, which would prevent them inserting into Quark inventories using TileSimpleInventory.

The code for pipes inserting items seems to properly support capabilities, the pipes just do not release any themselves.