Hi,
Sorry for not familiar with the query.
If you want to exclude computers belonging to one group for the group policy , the security filter can be used to do this.
Add all the computers in that OU into one security group, for example named group1
Open the gpo delegation, select the authenticated users : apply the group policy ,keep the read permission only.
Add the group1 and give it :read and apply group policy permission .
Update the group policy , only computers in the group 1 will apply the policy.
If i misunderstand you, please feel free to let me know.
Best Regards,