This has been submitted already over the past few days, but it didn't get traction and I think it's important enough to be worth another spin. Apple has relented and made 18.7.7, the latest security patch series for iOS 18, available to all iOS 18 capable models, not merely the limited number that were dropped for iOS 26 support. So if you (like me) had just grimly determined to skip 26 and hope to be ok until 27 being hopefully better, there is now a better option. If you did one of the 26 nag avoidance tricks and joined the iOS 18 beta channel you will need to turn that off for the 18.7.7 update to show up, and you'll have to scroll past the big prominent iOS 26 update notice to find it below as a smaller Also Available.
One thing of somewhat interesting note: as far as I can find they didn't release any standalone signed IPSW file for most devices like they universally have in general, only for a few old ones. Perhaps because if there is an actively signed IPSW they don't have infra in place to prevent people from downgrading back to iOS 18 from 26? So update has to be done from on the device not via Finder or iMazing or the like.