ESPRESSObin
Running FreeBSD on the ESPRESSObin works (at least v7).
ESPRESSObin v7
u-boot
In order to get FreeBSD booting properly on the ESPRESSObin v7 I got after ordering early 2019 I had to update the u-boot in the spi. For more information on something which worked for me, follow the instructions here: https://www.armbian.com/espressobin/ .
Apart from that standard EFI booting with the DTB file in the EFI partition seems to work. I might have had to adjust paths in the u-boot env.
Anyone who has a "virgin" device could add here.
Ethernet, switch
Depending on mode you want to run the ports you might want to read etherswitchcfg(8). To my best knowledge FreeBSD currently has no startup script support for this. I ended up writing my own one with a static configuration running BEFORE: netif.