In addition to 17.3 updates, Apple relased security updates and Rapid Security Responses for older devices.
Here are the specifics:
iOS 16.7.5 and iPadOS 16.7.5 were released for iPhone 8, iPhone 8 Plus, iPhone X, iPad 5th generation, iPad Pro 9.7-inch, and iPad Pro 12.9-inch 1st generation.
iOS 15.8.1 and iPadOS 15.8.1 were released for iPhone 6s (all models), iPhone 7 (all models), iPhone SE (1st generation), iPad Air 2, iPad mini (4th generation), and iPod touch (7th generation)
Here are the specifics:
iOS 16.7.5 and iPadOS 16.7.5 were released for iPhone 8, iPhone 8 Plus, iPhone X, iPad 5th generation, iPad Pro 9.7-inch, and iPad Pro 12.9-inch 1st generation.
iOS 15.8.1 and iPadOS 15.8.1 were released for iPhone 6s (all models), iPhone 7 (all models), iPhone SE (1st generation), iPad Air 2, iPad mini (4th generation), and iPod touch (7th generation)