Hello, there are two parts to the device offline issue — one was that we did not properly configure the API to forward the OpenVPN config to devices (the issue that you refer to) and the other is in balenaOS which you can track the status here: https://github.com/balena-os/meta-balena/issues/1101. I expect we’ll have this solved next week. As a temporary workaround, you could remount the boot partition as read/write, install the cert and reboot.
Regarding the dev variant, yes we have plans to make switching between dev and prod variants easy, hopefully real soon but I don’t have an ETA. It would be great if you could file an issue on the open-balena repo about this.