There were Rollei and Yashica TLRs with 35mm adapters. These were OK for vertical composition but awkward for horizontal composition. Both had waist level finders standard. There are 35mm backs for the Bronica ETR and SQ series cameras. I have the 35W back for the ETR cameras. It has the same 24X56 image area as the W back for the SQ cameras. I read somewhere that there was a prototype 35mm back for the GS-1 but that the camera went out of production before it could be manufactured. Some people have rigged up adapters which look like Rolliekins for other medium format and large format cameras.
If we're talking about 35mm capabilities of MF cameras, there is a 35mm back for the Mamiya 645 Super, Pro, and Pro TL series. I have one which mostly sits idle in the cupboard because Mamiya (foolishly in my opinion) passed on the opportunity to make the image area 24x56 instead of a boring 24x36. Their idea of "panoramic" is to provide a slide to fit in the dark slide slot which has a 13x36 hole cut in it. Whoop-de-do!!