Hi @MW ,
maybe this helps to start with:
https://www.reddit.com/r/PowerShell/comments/9h8ib6/report_of_permissions_for_ad_organizational_units/
One approach could be to query the OUs and OU ACLs and then work through the nested groups. Finally, determine the group membership of the users.
If you post your script here it is easier to help.
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(If the reply was helpful please don't forget to upvote and/or accept as answer, thank you)
Regards
Andreas Baumgarten