This is a generic question and no one can answer it without knowing more information and requirements.
You can go through below link for supported publishers for out of box integration
You can go through below link for SaaS applications supported integrations
There are various factors to be taken into considerations, for example how mature is your ITOM discovery and whether all CIs are available in CMDB, do you have entitlement details for all the Publishers and Products, for Publishers that do not have out of box integration, what is your plan of action ?
I would recommend to go to Now Create and check for SAM Pro implementation readiness checklist and Process Workshop presentations to understand the details needed prior to estimating the implementation efforts.
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Thanks,
Bhuvan
