There is no jailbreaking. You are given root access out of box[2]. They don't discourage external developers, they even provide a toolchain[1] to build for the device upon request. Hell, their CTO at the time (not sure if they still are) wrote some non-official software that people can install[4], and helped some of the initial members of the community get their stuff working. They just don't provide official support for external software on the device.
As for bricking your device: It will not hard brick, it may only soft-brick[0], as in, the display will not update on the rM2, because the software driving the screen needs to be updated to support the new OS. You can still SSH in and revert the changes and then downgrade. If you were silly enough not to write down your SSH password, or set up an SSH key and can't get into SSH, you can still recover your device[3] on your own.
I didn't know there's different kinds of bricking. It does NOT sound like having root access.
This big warning is on the front page:
> Warning: Toltec does not support OS builds newer than 2.15.1.1189. You will soft-brick your device if you install before support is released. See remarkable2-recovery for information on how to recover your device if you have done this.
> I didn't know there's different kinds of bricking.
There are two types of bricking[0]. A hard brick, where the device no longer functions, and may not be recoverable, and a soft brick, where the device is still working, but fails to boot to a usable state.
> It does NOT sound like having root access.
Could you clarify what you mean by this not sounding like you have root access? You have the ability to sign in to the device as the root user out of the box, which is exactly what root access is.
> This big warning is on the front page:
>
> > Warning: Toltec does not support OS builds newer than 2.15.1.1189. You will soft-brick your device if you install before support is released. See remarkable2-recovery for information on how to recover your device if you have done this.
Yes, I know about the warning, I wrote it. When it was less strongly worded, way too many people were ignoring the warning, trying to install toltec on an OS version that didn't have the offsets required for rm2fb yet, and did not write down their SSH password or set up an SSH key.
> a soft brick, where the device is still working, but fails to boot to a usable state.
Interesting. This means that if I ruin my grub I soft bricked the PC. As long as it's recoverable easily, I wouldn't consider that 'bricking'.
> Could you clarify what you mean by this not sounding like you have root access?
I just meant that if the device is no longer usable, you don't control it (as root). But you clarified that soft-brick is like a boot problem which, if easily fixable, isn't a problem.
This big warning is on the front page:
> Warning: Toltec does not support OS builds newer than 2.15.1.1189. You will soft-brick your device if you install before support is released. See remarkable2-recovery for information on how to recover your device if you have done this.