The EM780 is among the smallest mini PCs made by Minisforum, but it can support up to a Ryzen 7 7840U with eight Zen 4 cores and an RDNA 3 Radeon 780M. Despite the tiny case, Minisforum even managed to add active coolers for the processor and the M.2 storage.https://www.notebookcheck.net/Minisforum-presents-Mercury-EM780-palm-size-mini-PC-with-AMD-Ryzen-Phoenix-7840U-and-dual-USB4-ports.722862.0.html
Seeing that this "EM780" was never plugged in, and that several months have now passed, I very much doubt it was real. It was probably their EM680.