baseurl is http, but maybe should be https
If the Ubuntu tests are successful I probably won’t use OpenWRT on devices that have NVMe after all, but since I don’t know yet, I’ll keep this open for now.
Actually maybe I don't need this for openWRT.
This isn't in C but maybe it's sufficient or can be adjusted: https://github.com/raspberrypi/usbboot/blob/master/tools/rpi-otp-private-key
I think that the form with a button and hidden input fields is the cleanest, but my instinct tells me that it's too fancy: 
@shailaja You forgot to remove the script part in the template. Yes that's part of what I meant.
JS script is no more required as we'll send the created oauth_url from python code.
Or,…
It’s an overkill. If you prefer a button, you can still do a form with hidden inputs.
why not just have a <a href="{{auth_url}blablabla">Login via InoReader</a>? Then you don't need javascript.