Sort of? Kindle Unlimited itself is digital only, but the exclusivity clause only applies to ebooks I think, so in theory you could purchase a physical copy elsewhere.

I’ve pretty much entirely abandoned physical books. It’s just far more convenient using an e-reader which has a backlight for reading in the dark, fits thousands of books in a device that’s pocket sized, and let’s me instantly purchase, download, and start reading the next book in a series as soon as I finish the last one.

I do have physical books still, but I haven’t bought new ones in about a decade now.