So, wanna take a shortcut to a working accelerated Kodi system on a Pi or such, but now you want more than what you get out of the box? Lets do this.
WARNING: If you're wanting more than just LibreELEC gives out of the box but without much more hassle than LibreELEC, you might be better off just using a slightly-heavier alternative like [[ https://osmc.tv/ | OSMC ]].
== Difficulty 1: Existing Addons ==
The officially-supported way to add more functionality to LibreELEC is, unsurprisingly, via Kodi Addons.
The easiest way then is if you find Kodi addons already available for your purposes. Specifically, https://github.com/thoradia/thoradia has many of what one would need, like a torrent client (ie. Transmission or rTorrent).
== Difficulty 2: Create an Addon ==
If you don't see what you need already available as an addon, you could consider following [[https://libreelec.wiki/compile#compile_add-ons | the official instructions for compiling LibreELEC's addons]] combined with [[ https://kodi.wiki/view/Add-on_development | the official documentation for developing Kodi addons]]. But it //might// actually be easier to just compile on the device itself...
== Difficulty 3: Compiling on LibreELEC itself ==
First, to compile things you'll likely need some of the following tools. Unfortunately the `tar` that BusyBox ships with is insufficient for a lot of legitimate tar files that source code might come in, so here's some repackaging in simple ZIP files for convenience's sake:
{F1810}
{F1809}
Using busybox, the `./configure` runs will be full of `./configure: eval: line 1: expr: not found`. So you won't actually see the output. Lame! But it is doing stuff. But doesn't seem to work entirely in the end?
[[ https://www.gnu.org/software/mes/ | GNU Mes ]] might help with the boostrapping problem a bit, but you still need an actual compiler probably to start all of this.
https://developer.arm.com/tools-and-software/open-source-software/developer-tools/gnu-toolchain/gnu-a/downloads has tools that could be used for cross-compiling, but cross-compiling is a PITA.
https://elinux.org/Toolchains might be the best place to look, and to avoid cross-compiling maybe https://elinux.org/Toolchains#musl.cc ?