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 Open Source
Works with mainline Linux kernel and open source Mesa Panfrost drivers.
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.
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...