It was reported by @podmaz that some of the aspect ratio problems were corrected in retroarch 1.7.9. I haven’t tested it myself to validate it, but it could be worth looking into. Keep in mind though, that he had problems with having it work with Lima drivers.
Inadvertently, as @Lix mentioned above, perhaps just by not using Lima, he may have gotten it working.
@apple - Enter is what Start is mapped as.
However I think either @Lix has a different binding to enter the menu, as this isn’t the normal way. You can have “select and start” as a method. This is what I have it set to.
By default, entering the menu is achieved by pushing “SHIFT + MENU” - which in essence, is similar to a laptop’s fn key. This triggers the ESC to be pushed, which will enter the menu.
If you’re feeling adventurous, you can actually have the entire screen rotated 90 degrees, and play 1942 (or any portrait orientated games) as s side scroller. You will just have to map an alternative custom set of keys. Or alternatively, hold your Gameshell sideways; like a wonder swan, and use the keys awkwardly.
Stretching the image just looks nasty. But each to their own.