As per Gostev’s latest digest Veeam now has a site that you can go to for seeing anything that integrates with Veeam like Storage, S3, etc. No more visiting the “Unofficial” page in the forums.
Check it here - https://www.veeam.com/alliance-partner-integrations-qualifications.html
You can filter with the dropdown lists.
Example of S3 with Immutability - https://www.veeam.com/alliance-partner-integrations-qualifications.html?ad=menu-solutions&type=object-storage-target&product=vbr&programCategory=objectImmutable