Might be useful: https://github.com/seemoo-lab/AirGuarg, a third-party Android app, can force an AirTag to make a sound even if Apple hasn't determined that tag has been following you (the BLE characteristic is unauthenticated: https://github.com/seemoo-lab/AirGuard/blob/main/app/src/mai...)

HN discussion: AirGuard: Protect yourself from being tracked by AirTags and Find My accessories (298 points, 150 comments) https://news.ycombinator.com/item?id=28577951

AirGuard is great. They optimized the app to the point that it doesn't even show up in my Android device's battery usage statistics anymore. It's a set and forget app that scans for AirTags in the background automatically, but also when you trigger a manual scan. It's free and open source.

Apple's Tracker Detect app for Android (https://play.google.com/store/apps/details?id=com.apple.trac...) doesn't have automatic scanning, and requires the user to open the app and tap the button to manually scan for AirTags. It also forces the user to wait 10 minutes before they can make the AirTag emit a sound. I'm glad that the Technical University of Darmstadt made a better solution and released the source code, too.