Can we add external users to Sharepoint online site collection without sending invitations? I dont want to enable anonymous access and B2B
Yes, by using CSOM you can invite external users without sending them an invitation. However, users will only get access to SharePoint after authenticating with a Microsoft or AAD account and accepting the invitation link. As far as I know you can't just give them access.
I know there's a process where you could do so with B2B, but don't know exactly how that works.