301 redirect from Blogger to a new website - is it possible?

I'm migrating a website for a client who used Blogger for blogging up until now. So I'm trying to figure out how to 301 redirect their Blogger blog to newwebsite.com/blog

I've been googling for an hour now, but the solutions I can find all suggest using JS window.location or meta refreshes (both of which are supposedly bad for SEO). So no actual 301 redirecting.

Anyone know if it's possible at all? Cheers

Edit: Just to clarify, Blogger does have a built-in redirection feature, but unfortunately it only lets you redirect internal URLs. Like myblog.blogspot.com/post-1 to myblog.blogspot.com/post-2. Not from blogspot to another domain.