I was an early adopter of Hardkernel's Odroids, for better (size, performance:cost) and for worse (longevity).
This looks like a winner in every way.
x86_64 for longevity and support, tested with Ubuntu $latest LTS
decent CPU, better than Raspberry Pi
RAM up to 64GB, two SO-DIMM slots, up to 32GB per slot
M.2 NVMe storage
2 x 2.5Gbit Ethernet ports
2 x SATA 3.0 ports
Intel UHD Graphics, HDMI 2.0 and DP 1.2 video outputs
> Supports i2c, UART, USB, and hopefully manual pin control too.
From the set of pins provided I wouldn't get any hopes up for manual pin control. All pins are single-function, USB pins are almost never switchable (because they're high-speed analog-ish PHY functions), and UART & I2C are not GPIO-capable functions on most x86 platforms.
This looks like a winner in every way.