@jmorris off-topic but i have this sound card called "RME BabyFace Pro FS". it has pretty cool idea for FPGA's: the mixer is an FPGA. With this topology it can reach 1 ms latency for audio. And i.e. a firmware update contains also potentially update for the FPGA. Pretty clever hybrid approach IMHO.

Before I got this sound card I was not really sure where application wise it would make sense to have e.g. a SoC combined with FPGA but this product made me understand it a bit better.

I also own one small lattice FPGA. As soon as I get an idea how to use it e.g. with RPi for similar hybrid thing I'll definitely will PoC something. Lattice's have the benefit of having open source FPGA stack and since I also have a SoC FPGA does not have to have too many logic ports.