Well, TrueNAS Scale isn't exactly designed to be run on a SoC, it's more of a normal linux distro for NAS/SAN Servers. Hence most of it is open source and there is active upstreaming efforts. Plus the entire ACL thing is native to ZFS already, it's just the glue layer that's missing in Linux. For Linux it's presented in an XAttr for compatibility, for Solaris it's part of the proper permission bit fields.