I've been using
Courier Prime as a default monospace font on my Glo for a while (with a
patch so that the ePub reader uses Courier Prime when it sees the
font-family: monospace; style) and am quite happy with it.
I corrected the PANOSE weights which were all set to Thin in the original, they just needed to be changed to Book or Bold as appropriate to work properly with the KePub reader.
I also tweaked the line spacing metrics a bit so that it better matches the line spacing of Kobo's default serif/sans-serif fonts Georgia and Avenir Next, and other built-in fonts like Amasis. Without the tweaking the line spacing can look a bit uneven when there is a transition between Courier Prime and the other fonts.
Edit: I haven't got the line spacing quite right yet, it is closer than it was but still not exactly he same as Georgia, Amasis, etc.
The hinting in Courier Prime is good, so I left it in place. With a monospaced font there is no kerning and it doesn't matter so much if the hinting results in a small positional change to the letters.
This font has real italics, unlike some of the other Courier fonts which just use oblique as a substitute. It is not quite as heavy as Georgia, Amasis, etc. but it is not so light that it looks out of place alongside these fonts. I didn't change the weight at all.
(The name "Courier Prime" is reserved, so under the terms of the OFL I had to change it.)
It is strange that the Kobo firmware doesn't have a monospace font, but is there any reason they couldn't include a free one like Courier Prime?