I've tried MANY different models of tempered glass for the Jolla C.
The best 2 that I've found are the
- HTC Desire 626S (I don't know if the regular Desire 626 is the same or not)
- Motorola Moto G2

See the picture for the fitting results

The Moto G2 covers almost everywhere, but the HTC one looks nicer (covers less though)

Found a better one? Tell me and I'll update this post!

(Moto G2 is the one with the rounded corners)