I haven't really looked into it much but with the overwhelming number of cameras for sale I figured it may have been far easier to just ask first!

Such a camera does not exist at this time. Leica briefly offered a digital back - the Digital Modul R - for their 35mm R8 and R9 SLR cameras but discontinued it in 2007. I suppose you could find an R8 or R9 with the Digital Modul R back but it will likely be very expensive.

In the early days of digital photography a company long forgotten tried marketing a digital back for 35mm cameras but it too quickly vanished.

Hasselblad and Mamiya medium format cameras offer digital backs that replace the film back which makes them a sort of hybrid film/digital medium format camera.