What is your experience with using OVF for data protection?

[vwmagic]

Background:
We have already implemented a backup tool (For instance, CommVault like) to back up all VM's (about 800 VM's). We are also seeking a method for Ransomware protection as 3rd protection, in case both VM's and backups got attacked. We prefer not to pay any addtional money, or as less as possible. So, somebody here suggested to use OVF downloads. Did any of you use such method for Ransomware protection and make any sense to you? If yes:

1.  How would you store all these downloads?
2. How can you automate the OVF downloads for so  many VM's, manually do it one by one seems time consuming?

Thanks for your inputs in advance!

[vwmagic]

Could you please elaborate in details?

As i understand, you need to take VM offline before you can export OVF, so, regularly shut down all 800 VM's, and interrupt business, that's a lot of efforts?

Also, how did you manage all these OVF outputs, what retention policy, where you store them?...