Not sure if this question is relevant. can we use SMTP server of Gsuite / google to connect with mautic?
It can be added yes.
So instead of mautic + postal can I do mautic + Gsuite?
Will there be any issues?
Since gsuite is in shared IP do I still need to do a warmup?
I have a list of 1000 and I want to send promotional emails/ valuable content and direct them to my blog and courses
Yes you can and there will be no issues. just warm up the account and you can send.