So here's where I start.
The description should make clear my opinion on the whole FOV thing, I wanted to take a photo but even my wide angle gopro clone couldn't take a picture the way my eye does.
My thought is close the gap between my eyes and the lense, get as little leakage as possible, and put the phone as close to the lense as I can, like pressing a magnifying glass onto the middle of the tv; you're never gonna see the edges of the tv.
Anyway, remembering seeing the lenses you get in your bog standard original cardboard, 25mm biconvex stuff with a 45mm focal point, I didn't think it was worth bothering with those.
I happened to stumble across an article about a diy google glass project using the optics from some 2007-style video glasses. These things look like they have a 10mm gap between the lenses and the screen, so that's a good starting point.
The glasses, about $50 these days.
Looking around for a bit, I couldn't seem to find much else on them, but it did make me think of magnifying glasses, bottom right, which claimed a working distance of 0.5-1cm, so yay, I'll order a pair.
More video glasses lenses on the left, the zoomy zoom glasses on the right.
A problem I can see with the zoom zooms's is that although the lense focuses on things half a centimeter away, the lenses themselves are so far from the eyes at that point. Oh well, worth a shot...
Anyway, out of curiosity I grabbed out an old cardboard and started playing around with its lenses. By default they're 15mm away from my eye and 45mm away from the phone.
I decided to shove one of the lenses onto my eyeball, as close as I could, and see what the focus then was like.
When the phone was touching my nose, everything had perfect focus, and close to my entire vision was covered, spare two small slivers (one of which is usually just blocked by my nose anyway).
(I feel kinda let down by google on that one).
Anyway, so the lenses work and they work great. Problem is, how to get them so close to my eyes?
At first I thought just mount them on something with a bend to avoid my nose, but that's not as close as it can be and I don't want the nose ridge in the way.
A cutout for the nose wouldn't work because I want these damn things as far into my eye sockets as I can manage.
I'm currently thinking cones, like the ones in the rift dk1/2, but much smaller. Have them fan out super quickly, and press the device onto my phones screen. Once all the distances are worked out I'll build a housing around this all with straps.
Thinking now, I could even conform the cone enclosure to my face, put on a little fabric to make it comfy.
First thing though, make the cones and maybe a rig to get the distances perfect.