I believe you already played with /usr/src/sys/amd64/conf/MINIMAL kernel?
One of my buddies switched from TrueNAS SCALE to FreeBSD based zVault and is more then happy:
- https://vermaden.wordpress.com/2024/04/20/truenas-core-versu...
He does not have really high expectations - besides having about 2TB of data he runs one Bhyve VM with Linux 'Home Assistant' and one FreeBSD Jail with 'Plex Media Server'.