Greetings! I've been digging into the example queries provided in the standard query library. There are multiple queries referencing the

com.apple.SoftwareUpdate

domain, and according to Apple's Developer site that domain and its options are deprecated. It has me wondering, are those options still useful despite being deprecated? (i.e. is that why they're still in the FleetDM examples?)

Those examples likely pre-date the deprecation by Apple. The query would still be useful for older devices though!

Deprecated doesn't mean they don't work, it means Apple will remove them in the future. Apple did say it will be removed next year. Those settings do still exist in Tahoe.