Qualcomm has rebranded a Snapdragon with quadruple Cortex-A78 cores (and 4 small Cortex-A55), from the expensive smartphones of 2021, as "Dragonwing" QCM6490 and they now sell it for embedded devices.

There are at least 3 or 4 SBCs with it, in RPI sizes and prices.

Cortex-A78 is much faster than the Cortex-A76 from RK3588 or the latest RPI (e.g. at least 50% faster at the same clock frequency), and its speed at the same clock frequency does not differ much from that of recent medium-size cores like Cortex-A720 or Cortex-A725.

Cortex-A78 is the stage when Arm stopped making significant micro-architectural changes in medium-sized cores. The later improvements were in the bigger Cortex-X cores. The main disadvantage of the older Cortex-A78 is that it does not implement the SVE instruction set of the Armv9-A ISA.

While mini-PCs with Intel/AMD CPUs are usually preferable, for an ARM SBC I would no longer buy any model that has older cores than Cortex-A78.

Besides the Qualcomm Dragonwing based SBCs, there are also Cortex-A78 based SBCs with Mediatek or NVIDIA CPUs, but those are more expensive.