My accessory toy bag contains the central-area spot magnifier attachment and, the most useful of all, the Pentax 67 (later model) right-angle finder
(see pic).
This has continuously variable dioptric correction in + / – direction (the setting will vary according to the lens in use — wide angle or tele, near focus or far) and provides for precise focus in low light — a known and aggravating problem with the f4 lenses when used with a polariser, for example. Earlier iterations of the magnifier have unmarked dioptric correction. The right-angle finder has provision for a rubber hood to further enhance viewing and excluding stray light, or even protecting your spectacackles from scratches.
Research right-angle finders carefully. They are widely available, but the Pentax 6x7 often show up with active fungal infections or internal dust or both. This cannot be satisfactorily dealt with and the optical section of the magnifier is sealed within the barrel — only the crystal glass prism is serviceable for e.g. removing dust etc. If something is described as MINT, ask for photos to prove it. A magnifier with fungal infection will be like eyeballing a tarantula every time you attach it to the camera — truly irritating. I couldn't stand that with my first magnifier and threw it out.
The chimney hood is another option worth exploring. It has a corrective viewing ring and cut-away hood attached. The waist-level finders often turn up on the used market with stubborn dust within that is a quandary to treat.