That configuration is already possible in Windows with the “DelayedAckFrequency” parameter and in Linux with the “quickACK” setting, but it’s unrelated to congestion control, and it will neither “solve” bottlenecks nor “turn TCP into UDP.”

Congestion control (the purpose of BBR) deals with the bottleneck problem. Delayed ACKs are an optimization to reduce protocol overhead. Indeed there are problems with delayed ACKs when combined with Nagle’s algorithm and an application that doesn’t send a steady stream of data, but it has nothing to do with the topic of this thread.