No more than Apple gave its software business away when it opened the App Store. Are you also worried that Apple isn't doing enough to monetize iMessage and FaceTime?
These are all "free" services that are bundled into the price we paid for our Apple hardware. The more useful these software-based services are to us, the more value we get from our hardware purchase and the more likely we'll keep buying Apple hardware for years to come. And if we buy Apple hardware we're also likely to buy Apple services.
Any time Apple sells a package of Chipolo ONE Spots at Apple.com or at an Apple Retail Store, Apple will make a profit. Not as much as if they'd paid a factory to make AirTags, but it's still money in Apple's pocket, with far less capital invested. And because Chipolo has a motive to sell more Chiplo products, they are also promoting Apple's Find My service and the Apple brand in general. The bigger the Find My brand name becomes, the better for Apple.
The Find My infrastructure is just one more bit of cement between the bricks of the walled garden. Apple doesn't have to manufacture or monetize every brick in that wall because in the end, Apple is still the primary beneficiary of having that wall. Every feature and service that enhances the customer's experience helps ensure that your current iPhone will be replaced with a new iPhone, and that you'll replace your Windows PC with a Mac because it will work better with your iPhone, and when you decide to get a smart watch it will be an Apple Watch, and that your wireless headphones will be AirPods, and that the subscription services you buy will be more likely to be Apple subscriptions...
And did they do this to avoid anti-trust scrutiny? No. Apple is under no legal obligation to open Find My (or FaceTime, iMessage, iCloud, etc.) to third parties. The real legal problems come when Apple does open things up - then the companies doing business with Apple (or who would like to gain access to Apple's customers) start filing law suits or complain to government regulators about how unfair/restrictive Apple is.