Appreciate the writeup! Reading towards the end, it sounds like a good idea would be to fully discharge the controller's battery before disassembly to avoid some of the risk during reassembly, supposing it's functional enough to power on for that. Also given the possible parts loss, disassembling over a bowl or similar might help prevent losing anything. Honestly it's a good idea anyway just for holding screws.
Also for any interested in some visuals, iFixit has a teardown video here.
Quick search surfaced the following for Linux:
k3b, where the source repo states bluray burning capabilities.
xfburn also mentions bluray burning capabilities.
For Windows, albeit old and unupdated, I know the following still works for other purposes (never tried bluray burning/writing though):
ImgBurn mentions bluray burning/writing capabilities, but never tried it.
Bonus: not capable of bluray burning/writing but just fun to mention for any still into ripping/writing to discs on Windows:
InfraRecorder, simply a classic, and it's open source!