I do not know much about progressive profiling but is this possible?
It's possible, but it isn't related to Progressive Profiling.
Progressive Profiling ("ProgPro") is when you show only a max number of empty fields at a time to someone whose pageview/session is already associated with a known lead.
What you're talking about is the "Lead Lookup Form" concept, which involves performing that association in the first place for a session that starts out anonymous.
Describing it at a high level, a Lead Lookup Form is a Marketo form with just the Email Address field. When someone submits the form, a special Marketo page is repeatedly polled (say, every 100 milliseconds for up to 3 seconds) to see if the person was already in Marketo or if the form post created them in Marketo. The end user doesn't see this, of course, it happens under the hood. Then you can redirect them to their next page based on whether they're net new as of just now, or were an existing lead. You will need
The Lead Lookup Form also has Known Visitor HTML enabled, because the session may already be known at the time they hit the page. In that case there's no reason to have them fill in their email address, you can take them directly to the "existing lead" LP.
You need a Marketo-savvy developer to implement the Lead Lookup Form but it's not difficult.
