I think LTS gives you that. You already have “no auto updates”. LTS adds “and a guaranteed upgrade path to the next LTS”. So your NAS just runs, and every two years you install a major version upgrade. Optional minor upgrades in between, from 26.04.2 to 26.04.2.1 &c
This feature request came out of the 6-month release cadence discussion. New versions of TrueNAS every 6 months It not getting traction is a completely acceptable outcome.
At least now there’s a place to vote for it and comment. ixSystems can then gauge the response and see whether it’s worth going for.