Redirect to user page on front-end login?

Can I modify a Theme Markdown file to force a redirect upon login based on grav.user.username or the first group that appears in their accounts YAML file?

So, user littlepup (first group in account YAML is puppywrestle), is redirected to:
via something like this:
/projects/{{ grav.user.username }}

Or even better, redirected upon login to:

Thanks in advance!