iPad mini

iPad2, iPad3 and iPad mini1 can only be updated to iOS 9.3.5 (WiFi Only models) or iOS 9.3.6 (WiFi & Cellular models). Apple ended update support for these models in September 2016. Your iPad cannot be updated to iOS 10 or later major versions of iOS, as the internal hardware does not meet the minimum technical requirements for new versions of iOS/iPadOS. 

Having reset your iPad to factory settings, all previously installed Apps were wiped from the iPad - and, if still available, may need to be reinstalled.

However, you need to consider that compatible Apps for your iPad are increasingly difficult to find - as most App developers have dropped support for 32-bit devices and iOS versions preceding iOS11/12/13. As older versions of Apps are removed from the Apple App Store, you’ll not be able to (re)download or install them - which may severely limit the usefulness and utility of your iPad. As such, if you want or need to access most current Apps, requiring a more recent version of iOS than you iPad is able to support, you’ll need to consider replacement of your iPad with a newer or current model.

Of current models, even the entry-level iPad9 has specifications and capabilities that will massively outperform you current iPad, is compatible with iPadOS 15 - and the vast majority of current Apps.

I hope this information provides succinct clarity as to your available options - and the limitations of your current iPad.