As per title, which of these do I want when reassembling the rear triangle?

Threadlock

Ha, I RTFM. It’s blue threadlocker. thanks!

Grease on the pivot and threadlock on the thread!

Both, in the appropriate places.

Bearing depends on the frame if its installed dry/grease/retaining compound.

Bolts/pivot axles I would install with grease on the shank, loctite 242/3 on the threads (think if you want to apply it to the nut or bolt depending how its assembled).

Threadlock and grease, each on it’s place

As above,combination of both. You might find the bikes website has a diagram showing where to use each. YT certainly did/do.

A drop or two of threadlock on the first few threads, screw it in half way then grease the rest and torque to the correct NM, that is the most important bit, I’ve never had a bolt come loose with that method.
I had a nightmare with factory threadlocked bolts on an old kona years ago, had to drill out two bolts as there was dried threadlock all over the entire thread and shaft, ridiculous. A mate once over threadlocked a pedal to his right crank arm that kept coming loose, it took him hours to remove with hefty tools and a lot of swearing. Always go easy on threadlock, it’s in little bottles for a reason.

Don’t use it.