There are many variations of ‘swallowed him to the hilt’, ‘swallowed him till his nose was buried deep in pubes’, blah, blah.
I have to say, though, that whenever I read the phrase ‘swallowed him whole’ it always reminds me of two things:
(a) that X-Files episode in which a Native American legend comes to life and is forced into eating people to cure them of their illnesses (it made me hurl), and
(b) Moby Dick.
I think the latter has real m/m possibilities.