Thanks for a very useful post!
It looks like devices on iPadOS 17.7.10 are using Root Store version 2024040500, i.e., the Root Store that was updated for iOS 17.4, iPadOS 17.4, macOS 14.4, tvOS 17.4, visionOS 1.1, and watchOS 10.4.
There are three certificates that are expired in the store, including the Apple Root Certificate Authority (exp Feb 10, 2025), Visa Information Delivery Root CA, and Baltimore CyberTrust Root. Several more expire in 2026 and 2027. Interestingly, according to the webpage for OS 26 certificates, the Apple Root Certificate Authority has not yet been updated.
FWIW, I haven’t run into any problems so far while using iPadOS 17.7.10 on my 6th generation iPad.
Updated to add: OS 26 does not contain certificates for Visa Information Delivery Root CA or Baltimore CyberTrust Root. I don’t know if those are no longer important or if they have been renamed.