What are the best drawing apps for iPad Mini 1 running iOS 9?

As already outlined, very few Apps are likely to be available for the iPad mini1 - or iPad1 through iPad4.

iPad5, iPad Air1 and the iPad mini2 were the first of the 64-bit architecture iOS devices - some of which are also now obsolete due to their age. For practical purposes, many of the major App Developers limit support to the current and perhaps one or two prior major versions of iOS/iPadOS.

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 17.7.3

(*) obsolete

Newer models are all able to be updated to the current version - iPadOS 18.2

• 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)

Your iPad mini1 is obsolete - along with other 32-bit architecture iPads. App Developers have dropped all support for 32-bit devices - and all Apps for 32-bit architecture devices have been retired and removed from the Apple App Store. As such, you will not find many (if any) available Apps for such an old iPad.

All current Apps are designed for 64-bit hardware - and cannot be installed on 32-bit devices.

Sorry, but your iPad mini1 has had its day...