I don’t know about pagetracker but the allowlinker in a somehow familiar term for me.
AllowLinker is the term of a plugin for google analytics called Linker. This plugin smooths the process of applying cross-domain measurement as described in the Cross-domain measurement guide for analytics.js
On the destination domain, The allowLinker field is provided, which when
true instructs analytics.js to check for a linker parameters in the URL. If the linker parameter is found and is valid, it extracts the client ID from the parameter and stores it.