espressobin seems to use DDR4 - and as far as I'm aware, the only computer with free DDR4 RAMinit is the Talos systems.
USB 3.0 is often implemented with proprietary software too.
The onboard 802.11 a/b/g/n +ac/ 2T2R wifi relies on proprietary software functionality.
It seems to have 4MB of SPI NOR flash, which is a place where proprietary software can go - if there is in fact no proprietary software in u-boot - it always comes on the SBC.
It'll take at least 6 hours to investigate properly.
