I find this distinction unnecessarily nitpicky in this context. A BCI can be implement using EEG as an input so yes, you can definitely make a BCI using PiEEG.

130dB SNR is also not too shabby for a low-cost device, I wonder how it compares in a real world scenario with some of the OpenBCI offerings. For now at least it seems to be a cheaper option to OpenBCI Cyton with a comparable performance, unless I missed something.