I was just about to post a similar topic, glad I found this.
A couple of times I have used the Ilford XP2 single user camera and I really liked it.
But they cost almost $20 CAD and the film inside is only worth $10 CAD so I'm basically spending $10 each time to 'rent the camera'. So I was looking for something similar but reusable.
First that came to mind was the Kodak KB 10. It's basically the same specs but actually slightly more primitive as the flash fires every photo. You can apparently just not load batteries though
Then I was interested in the Harman reusable camera with the luxury of a flash on/off switch, but if it has a fun-house lens then I am not interested.
So then I was thinking the next step up up would be something with several apertures.
This stock photo showed up and I'm quite curious about it, but no branding at all.It appears to allow several apertures and several ISOs
https://www.dreamstime.com/stock-ph...-dubious-quality-isolated-white-image52144454
EDIT its an AGAT 18K
https://www.photothinking.com/2018-10-15-belomo-agat-18k-plastic-fantastic/
And this Pentax Pino 35 is basically the same thing but from a more respectable brand
http://camera-wiki.org/wiki/Pentax_Pino_35
I realized that most of the plastic cameras Kodak put out from the 50s-80s (Brownie, 'Star' series, Instamatic, 110 cameras) are all just simple box cameras like the Kodak KB 10.
But then I thought about what might be the next level of advancement.
I note the Instamatic 404 has a selenium light cell tied to aperture (and I actually own one for display)
https://en.wikipedia.org/wiki/Instamatic
but I have no interest in reloading 126 cartridges.
Note, I realize some of these last ones probably have a glass lens.
So I'm curious if there was a plastic 35mm camera with that small level of automation? What about a switch to change between two focal lengths? I think that would be the very limit of the kind of 'advancement' I'd be looking for but I'm curious what is out there.