What are the iOS requirements for installing Microsoft 365 Copilot on iPad?

Unfortunately, your iPad is obsolete. The first generation iPad Pro 9.7"/12.9" 1st generation can be updated to iPadOS 16.7.x - but neither support iPadOS 17 or later.

The majority (if not all) of available Microsoft Apps require iPadOS 17 or later. Microsoft generally support the current and immediately preceding major versions of iOS/iPadOS.

Whilst many App titles remain available and compatible with your iPad Pro, if you want or need to access to Apps requiring a more recent version of iPadOS than your iPad is capable, your only option is to replace your iPad with a much newer or current model that supports iPadOS17/18. As is, you choices of available Apps are limited.

For information, here is a list of the highest version of iOS supported by the older models of iPad (for simplicity - “generations” are shortened to a number) that are restricted in their ability to be updated:

32-bit devices (obsolete)

iPad1 - iOS 5.1.1

iPad2, iPad3 and iPad mini1 - iOS 9.3.5 (WiFi Only models), iOS 9.3.6 (WiFi+Cellular)

iPad4 - iOS 10.3.3 (WiFi Only), iOS 10.3.4 (WiFi+Cellular)

64-bit devices

iPad Air1*, iPad mini2 and iPad mini3* - iOS 12.5.7

iPad Air2, iPad mini4 - iPadOS 15.8.3

iPad5, iPad Pro (9.7"/12.9" 1st generation)* - iPadOS 16.7.10

iPad6, iPad Pro (10.5"/12.9" 2nd generation) - iPadOS 17.7.5

(*) obsolete

Newer models are all able to be updated to the current version - iPadOS 18.3.1

• iPad Pro 13" (M4)
• iPad Pro 12.9" (3rd generation and later)
• iPad Pro 11" (1st generation and later + M4)
• iPad Air (3rd generation and later + M2)
• iPad (7th generation and later)
• iPad mini (5th generation and later + A17 Pro)

sadly no, it's up to the app develoer in this case ms what the ipadOS requirements are