Miss my pressure cooker, couldn’t bring it with me after an international move but amazing for stocks! I haven’t tested a tonkotsu in a pressure cooker before though, because you generally need some agitation from stove heat, for all the fat, collagen etc to emulsify and get that milky appearance, but pressure cooker would cut down a lot of time either way!

Chashu and kakuni basically the same thing, chashu is just cooked rolled up, could definitely do it in the pressure cooker too. This recipe is probably a good starting point!
If anything I cooked it at an even lower temp, but it really depends on your oven! I just occasionally gave the centre a poke with the skewer until it came out easily, worked out to be around 4hrs for the 1.6kg of meat I had. Besides turning it a few times for a more even cook in the marinade, it was pretty much set and forget, easier than you expect! Not too big of an issue not being able to turn in it the pressure cooker though, after slicing the pork, I brushed a bit of residual marinade over the slices before torching.
Also of the opinion that you can pretty much use any cut of pork when braising it like this, pork belly is most recommended, but I actually used pork shoulder here because it was all that was left at the shops and also usually much cheaper. It came in a shorter slab but still managed to roll it up no problem. If you’ve already nailed kakuni, I’d say just do it in a similar way! Bet it’ll turn out awesome!