Well this post is actually "release" (as in distribution) related. It can even be interpreted (I do not know the posters intend) to add rpi to our releases.
Currently official released versions (which is what the thread is about) exist only for the platform for which we provide on sourceforge.
Any platform not represented on our sourceforge, can be attempted to be installed from source.
"Distributions" available via Linux repositories, or other channels, are not made by the Lazarus team.
And we have no influence on them. In most cases we do not even know the people who put those repositories together.
We do not currently have any ready release builds for none Intel. (i.e. arm on rpi).
I do not know if anyone is going to volunteer to build them. (including testing, and maintaining fixes for the new platform).
So anyway, as I said this thread is meant for the existing release process, and existing targets.
So for a new target, as Juha said, please open a new thread / or consult the mail list (different audience, widening the reach for potential contributors).