The BCU was delayed by Xilinx who makes both the FPGAs and the board that is the BCU1525. Xilinx is delayed due to unavailability of other components used to make the BCU, not the actual FPGA itself. SQRL is facilitating the BCU orders, if I understand correctly, not making the boards.

Any project could be delayed if they needed the same components that Xilinx is waiting for, Acorn included.

Supply chain stuff is complicated, and most companies try to have multiple suppliers for most components to prevent this from happening. Sometimes there is only one supplier for a critical component, and that supplier has a problem, well, you are SOL. It's also not usually easy to get a new supplier online in a short period of time, especially if high volumes of components are needed. Not to mention those suppliers also have existing customers with contracts...