So, you have a group of users, but you can’t advertise your Task Sequence to users. If you enable Asset Intelligence to inventory the TopConsoleUser for a machine, you can extract all machines based on the TopConsoleUser for that group.
select distinct SMS_R_System.Name from SMS_R_System inner join SMS_G_System_SYSTEM_CONSOLE_USAGE on SMS_G_System_SYSTEM_CONSOLE_USAGE.ResourceID = SMS_R_System.ResourceId where SMS_G_System_SYSTEM_CONSOLE_USAGE.TopConsoleUser in (select distinct UniqueUserName from SMS_R_User where UserGroupName = ‘domainGroup’)
This will display all machine objects for users in group for domain. Now you can simply make a Collection based on this query and you can target your Task Sequence to these machines.