The Odyssey7Q+ is the best device for this (caveat: I work for the manufacturer and I helped design its anamorphic desqueeze function, so I'm a bit partial).
The Odyssey7Q+ offers multiple desqueeze options. It can desqueeze at 2x, 1.5x, and 1.33x ratios. Because a 16x9 sensor will yield a very wide frame on most anamorphic lenses, much wider than most people want, we also offer a cropped monitoring mode. This is a center extraction of the desqueezed image so that a traditional aspect ratio is shown that fills the screen, chopping off the unwanted sides of the image. The center extractions are a 1.33x desqueeze with 1.78 aspect ratio, a 2x desqueeze with a 2.39 aspect ratio, and a 2x desqueeze with a 2.67 aspect ratio. Other monitoring functions such as Pixel Zoom and exposure meters work as normal when Anamorphic Desqueeze is enabled.
The video outputs of the Odyssey7Q+ will show the selected desqueezed view so that other monitors on set have the desqueezed view. The Odyssey7Q+ is the ONLY device on the market that does this.
Note that the original signal is not altered at all. The recording is still squeezed, which is then best addressed in post.
Also note that the Odyssey7Q+ is the best recorder available for the FS7. If the FS7 has the XDCA accessory back it can output RAW, and if the Odyssey7Q+ has the Odyssey RAW Bundle enabled it greatly increases the recording capabilities available. The combination can record in 4K up to 60p or 2K up to 240p. Recordings can be made in CinemaDNG RAW files or in Apple ProRes. No other device available offers these capabilities.
You also mention using S-Log. The Odyssey7Q+ has an advanced LUT system included. There are a number of preset LUTs available and you can load an additional 140 custom LUTs. Preset LUTs include S-Log2 and S-Log3 to Rec709A and Rec709(800%). There are also Exposure Compensation LUTs for S-Log2 & 3 to Rec709A for when one wants to overexpose by 1 or 2 stops. That way you can choose to overexpose the image to reduce noise and increase effective bit usage while also viewing a "corrected image" so that you and your clients can see what you're doing. You can choose to have the Odyssey monitoring tools (waveform, spot meter, etc.) read either the source signal or the LUT-applied image. You can choose which signal goes to the different video outputs (there are three outputs, one HDMI and two SDI, and the LUT application can be selected individually) and you can choose if the monitoring tools are sent to the individual outputs as well. That way you can have a set monitor that shows the same thing as the Odyssey screen (perhaps a LUTTED image with a waveform reading the underlying signal), a signal to a DIT that is the original signal with no tools on the screen, and a signal sent to the Director/client monitors that is the LUTTED image with no tools.
I know that this is WAY more info than you asked and there's a lot that has nothing to do with anamorphic viewing, but I thought that you might like to know of the other advantages this presents with the camera you mentioned.