Signal Desktop Builds for Manjaro aarch64

[ninefathom]

Would you be willing to host/provide your build scripts / environment somewhere as well? We've been providing a non-ozone build for a while now over at https://forum.pine64.org/showthread.php?tid=9452 (providing the PKGBUILDS at https://gitlab.com/ohfp/pinebookpro-things), and maybe we could profit from each others work on it, instead of doing more or less the same work twice, while keeping things nicely open-source-ish all the while

Somehow I'd managed to miss those in all of my past forum-searching.  For the standard package @1.34.2-1, your PKGBUILD is virtually identical to what I'm doing.

For the Ozone package, the process was so arduous that I haven't even bothered trying to express it in a normal, reproduceable PKGBUILD as of yet; there was lots of "manual intervention" required.  To get to a point where somebody could simply PKGBUILD it, there would be two main things required:

• The first bit is electron-ozone.  There are really two separate things here.  The first is that some of the build flags from electron-ozone in upstream AUR aren't quite what we need.  Component ffmpeg is a must, for example, but upstream AUR has it disabled in their electron-ozone build.  The second is that, since Electron/aarch64 only supports cross-builds from x86_64, not native, we'd have to build on x86_64 but make the final package for aarch64.  Both of those things together tell me that we probably need a seperate PKGBUILD for a hypothetical "electron-ozone-aarch64" that A) has the needed build flags changed, and B) builds on x86_64, with added dependencies for cross-compile, but generates the resulting package for installation on aarch64.
  
• An overhauled PKGBUILD specifically for signal-desktop-ozone, which has a dependency on that electron-ozone-aarch64, and does the necessary patching and shoehorning to use the local electron-ozone-aarch64 dist instead of fetching from the web (which it tries really, Really, REALLY hard to do, in many places).
  

In all of that, I'd guess that two bits would be particularly challenging: getting makepkg to build a package on one architecture for installation on another, and all of the overrides to get the Signal Desktop build infrastructure to use a local Electron dist instead of upstream*.  If I can solve those two, then we might have a prayer of getting this relatively automated.

...any advice on the two challenges above, in particular?

* Simply modifying package.json to use a local Electron dist isn't sufficient.  Yarn will use that during some of the build steps, but then for the final stages of application build, yarn invokes electron-builder which (believe it or not) _totally ignores the Electron dist provided by yarn_, and instead figures out what version number of Electron yarn was using, and attempts to fetch that version number fresh from upstream Electron, for whatever crazy reason.