A few things came to my attention (thanks to muhomorr) regarding this topic.
First, unused static libraries can't do anything on their own. They're pretty much harmless.
Second, static libraries can be marked as "unused" by the OS and there are some internal triggers that can decide whether those libraries can be pruned. In other words: no need for adb (unless you want to remove the library immediately), the OS will eventually take care of that (it seems that in Android 12, this likely happens when the device is short on free storage).
Android 13 will make pruning of unused libraries consistent at each system boot and package install/removal.