There really are none, now.
No iPad made before late Fall 2015 is compatible with ANY Apple Pencil.
Older iPads are missing a crucial internal hardware screen layer needed for an Apple Pencil to interact with these older iPad screens.
This included the 2017, 5th gen, 9.7 inch screen iPad models, too!
There is no Apple Pencil-like, smart Bluetooth stylus that I can, honestly, recommend, currently for older iPad models.
The one I usually recommend, the Adonit Pixel stylus, has been out of stock, everywhere, for months, due to the worldwide pandemic, as there is no way to predict when this stylus will be available, again, if at all!
You have other stylus options like found everywhere, commonplace, capacitive stylii to use with your older iPad Air.
The better, more accurate versions of these are capacitive stylii with a clear disc tip for more accurate drawing.
Another type of commonplace capacitive stylii is the fine tip/ballpoint-like tipped, battery operated, so-called “active” stylus that uses a tiny battery to send small electrical signals to a fine point tipped stylus that mimics an actual finger touch.
All of these types of stylii suffer from varying degrees of line wobble when drawing angular lines. Some are worse than others.
The better of both the disc tipped stylii and the battery operated “active’ stylii are made by Adonit stylii.
https://www.adonit.net/pro4/
https://www.adonit.net/dash/
Like all commonplace, capacitive stylii, none of these stylii have screen pressure sensing OR palm rejection.
So, you will not be able to draw thin to thick or light to dark lines with these types of stylii.
The exception to this limitation is if the sketching/drawing/painting/writing app has a programmed/coded-in feature to drawing thin to thick/light to dark lines using velocity or how fast you draw a mark across the iPad's screen using a finger pr commonplace, capacitive stylus.
Some sketching/drawing/paining/writing apps have this velocity line varying marking feature.
So, you can write or draw on the iPad's screen with the palm or side of your hand down on the iPad’s screen and NOT make stray marks on the iPad's screen, with various sketching/drawing/paintng/writing apps, there are inexpensive special non-body electrical conducting, lycra- material based drawing/writing gloves for touch screen devices that allow you to lay the palm/side of your hand on capacitive touch screen tablet that isolates your actual hand from the tablet's screen so it will not send any electrical signals to the tablet’s screen and not make false or accidental touches while using an iPad or other capacitive touch screen device while writing or drawing.
Something like this found on Amazon.
https://www.amazon.com/Professional-Anti-fouling-Drawing-Tablet-Graphic-Right-Ha nd-Left-Hand/dp/B017R8M2JY/ref=sr_1_1_sspa?ie=UTF8&qid=1543548123&sr=8-1-spons&k eywords=lycra+drawing+gloves&psc=1
Many more makers of these types of gloves found on Amazon and in different hand sizes and colors, as well!
Best of Luck to You!
