Hexa core RK3399 with 1.8GHz. Well supported in Armbian. Cheap and small form factor extender which supports SATA, nvme M.2 (2280) and others.
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Pro 6 core HexaCore, compact nvme extender, 4GB RAM
Pro Many ports
4 x USB3
2 x USB2 available via pins
PCI-E available via pins
Rockchip 3399 with two fast A72 cores. Good heatsink limites throttling.
Pro Open Source
Works with mainline Linux kernel and open source Mesa Panfrost drivers.
Con Bleeding edge...
To have mainline kernel requires a bit of tinkering (e.g. installing Armbian). Panfrost drivers for 3d acceleration are not mature and crash sometimes...