Create a custom field for "Lead Status" > Map it to the "Status" field in Salesforce > Create an automation rule to detect the "Nurture" value > Automation rule sends an autoresponder email

Create a custom field for "Lead Status" > Map it to the "Status" field in Salesforce > Create a dynamic list to detect the "Nurture" value > Add as recipient list on engagement program to send emails

Create a report in Salesforce based on lead status of "Nurture" > Export and import into Marketing Cloud Account Engagement > Create a list from import > Add as recipient list on engagement program

Create a CRM Visible list in Marketing Cloud Account Engagement > Have sales also add these "Nurture" leads to that list in Salesforce > Create an automation rule to send email based on list membership