Questions about syncing Hub Site with Associated Sites

For each team site, the site owner can opt-in to sync Hub Visitors permissions - so as I said before, you can opt-in for some but not all associated sites. You can associate sites to a hub in "bulk" from the SharePoint Admin Center. From what I can see, you will need to manually opt-in to add the Hub Visitors to each associated site where you want to add the Hub Visitors group - though maybe you can do this with PowerShell. I think that before you go too far with this planning, you want to make sure that you have established the right type of site for each purpose. You can double check with this guide: https://docs.microsoft.com/en-us/microsoft-365/community/team-site-or-communication-site. Assuming that you have private team sites where you want to give READ access to an additional set of users, adding Hub Visitors to each site is a great way to do that. If the team sites are associated to Microsoft Teams, this gives Hub Visitors access to the files and lists on the site without giving them access to the Team chat and other resources associated with the Microsoft 365 Group for the Team.