The Pencil Pro needs to be paired and actively attached to your iPad (magnetically and wirelessly). That pairing step is what “registers” it with your Apple Account — there's no manual "Add to Find My" button for accessories like the Pencil. So here’s what I’d suggest:
- Make Sure Apple Pencil Pro Shows Up in Find My: Attach the Apple Pencil Pro to the side of your iPad Air M3. Wait until you see the "Apple Pencil connected" banner.
- Make sure your iPad is running iPadOS 17.5 or later: With a M3 iPad Air, it should already be at iPadOS 18.x, so you should be good there.
- On your iPad, open the Find My app > tap the "Devices" tab — not "Items." Wait a few moments — if all is well, you should see something like "Apple Pencil Pro" listed. If it doesn't show up, open Settings > Apple Account (your name) > Find My, and make sure Find My iPad and Find My Network are both enabled.
- Restart your iPad, then reattach the Pencil and try again.
If all of the above fails to resolve this issue, I would suggest that you contact Apple Support directly. To do so, simply select the "Support" link on the lower left-hand side of this forum's web page.