Interesting Twitter Thread at https://twitter.com/WolfieChristl/status/1565072082890784769
on ID correlations by Google, possibly including
Biscotti ID (seems to be the identifier that Google stores/retrieves in/from its ‘IDE’ cookie across different websites),
GAIA ID (a Google account ID),
IDFA/AdID (iOS/Google Advertising IDs)
and PPID