Is it a best practice to grant a Salesforce admin user account to a 3rd party vendor who's helping us in setting up hubspot for salesforce. I'm not completely sure if thats the right way or is there anything alternative.
Thanks in advance!
It is best practice to limit access to only the entities required to do the tasks at hand.
Hubspot provides a permission set which can be created/deployed in your org and applied to a dedicated integration user account, which has been configured for no access to any org functionality beyond the bare minimum. At that point you grant access using the permission set to specific features in your org (adjusting as necessary to meet your org's data access requirements).