It's a cool hack, but a terrible idea for a product. There are more components than the battery that will fail over a 10 year period (both in hardware and in software) - which is why ignoring notifications, and assuming that this product solves your problem is a big issue.
This seems incredibly pessimistic to me. Do you really not expect things to last for over ten years?
In my experience most electronic things - and especially things that are simple and solid with no wear and tear like an AirTag - easily last 10 years. I’d expect an AirTag to work for, at least, decades.
When the software is fixed we're back to thinking of the object as a single piece of hardware. My Gamecube and Xbox 360 have been working for (nearly) 20 years now.
Unless there's a known failure mode in these devices that gets worn down over time you should probably expect them to outlive you. The worst you'll probably get is corrosion from the AA batteries in the pack.
