@nitinct
UUIDv4 is a great library to generate that event ID, do not forget to pass it to both client side and server side ( media tags like facebook use these to deduplicate events) Read more around UUIDv4 below
https://www.geeksforgeeks.org/how-to-create-a-guid-uuid-in-javascript/
The more PII (hashed) you provide to vendors better the match rate which helps the marketing campaigns and some cases reporting ( google enhanced conversion)
For some of the vendors it is mandatory while some vendors are ok with IP address/user agent, so essentially it is not a blanket answer and it depends on each vendor.
We reached out to each vendor and got the must have and good to have properties for our use cases, reach out to marketing team/vendor to get that confirmation
Anil