Difficult - as the original iPad Air cannot be updated to iPadOS13+.
iPadOS13.x added Trackpad and Mouse support - that was lacking in earlier versions of iOS. There are many third-party keyboards available for iPad, so this remains possible - however, anticipated use a full laptop replacement may be ambitious.
You’ll need to carefully consider your needs - and ultimate suitability of iPad as primary computing device. iPad is a wonderful companion device, and with introduction of iPadOS13 (and soon to be released iPadOS14), the gap between iPad and laptop is closing.