This sequence of posts is about my first impressions of the SharePoint Advanced Management add-on features for M365/SharePoint Online.
There are four posts in total:

Site lifecycle features

This feature can find sites based on certain conditions and automatically apply a policy on them, and address site owners and have them remediate the problem.

Currently there are two types of policies.

Inactive sites policy, and
site ownership policy (in preview)

Policies can be simulated first, and only after checking the results activated.

Inactive sites policy

Identify inactive sites based on visits, edits, file actions and even Teams or Viva engage activity.
Send notifications to site owners or admins.
Possible actions: None, Set to readonly, Archive site.

Inactive sites policy page 1

Inactive sites policy page 2

Inactive sites policy page 3

Microsoft Archive

So, you can automatically trigger a site to be archived in M365 Archive after a period of inactivity.
However, M365 Archive currently has the following downsides:

You can only archive a complete site collection. This means that only sites that are completely, 100% inactive can be archived. If one file is being worked on, you cant easily archive it. NB: File level archiving is scheduled for the second half of 2025.
Reactivation of archived sites when a one or more files are needed again is pretty expensive
Archived sites cannot be searched through to see if it does or does not contain a file an end-user might need back. A end-user search feature is also in development for release in 2025.
Due to the combination of these three points, you run a high risk of running into high cost because you need to reactivate a large site in order to get back a certain file. This is the exact opposite of why you want archiving, which is to reduce cost for storage.
There is PowerShell support for archiving a site. This can be used to setup your own archiving process using M365 Archive.

Site ownership policy

Identify sites that don't meet organization's ownership criteria (minimum 1 or minimum 2 owners are the only options).
Send notifications to find new site owners or admins.
Possible actions: None, Set to readonly.

Site ownership policy page 1

Site ownership policy page 2

Site ownership policy page 3

My review comments for both site lifecycle policies

Filtering options are very limited!! We can only exclude max 100 sites. No filtering based on site property bag if you use that
Opportunity: Handle all classic sites, or all teams connected sites.
Risk: special purpose sites are hard to filter out due to limitation of 100 exceptions. Wild card URLs are not supported in the exception list.
Mails are sent from generic SharePoint address -> many people may not reply or take action.
Easy to configure and useful to improve governance.
Impact of the policy can be determined by running a simulation and investigating the results.
Microsoft Learn page - Site lifecycle management

Continue to Minor SAM features - page 4 of 4