[redundantly]

It's full 35mm. The sensor isn't directly exposed to the light from the lens. They've got a projector screen + periscope configuration going on.

https://petapixel.com/2023/10/06/a-20mp-sensor-in-a-film-can...

Not sure how I feel about this configuration, I'd like to know more about the amount of light lost with this set up, image distortion, etc.

[Clamchop]

Took me a while to figure out what you were talking about. So, the article mentions an older product by the same people that used your "periscope" arrangement, but THIS product is a m4/3 sensor hanging off the end of a ribbon.

[redundantly]

I provided the wrong link before. Here is the one I meant to share:

https://imback.eu/home/new-model/

But, yeah, I missed that it's a new version of the Back35.

Side note, their website is terrible.