Hello Hagai,
maybe you need to write a custom inventory for this. See this
link to see some examples, and another
link for an introduction.
Under Linux SSL certificates usually reside in the /etc/ssl/certs folder. But any distribution may handle the contents differently. You may find either .cer or .crt or .pem files for each trusted ca certificate or only a few files containing multiple certificates.
Best regards,
Hannes