The KeySmart SmartCard is a Bluetooth tracker compatible with the Apple Find My network. The key difference is that this is much flatter, meaning it'll fit in a wallet or ID card lanyard better. Like all third party AirTag competitors, it doesn't have ultrawide band (UWB) directional tracking.
Amazon has a 20% coupon for Prime Day sales on the product page, which stacks on top of another discount for the 1pk. Discount shows in checkout.
The 3pks aren't available direct from the US store any more but this ends up slightly cheaper than the current individual price there ($25.60USD if you can find a 20% code).
I've previously posted on the forum re wallet compatible options (inc cheaper Aliexpress knock off's) here.
Not compatible with android :(