Passquest and stone are solid. You can see in how the teeth are machined, very close to those of SRAM.

+1 to stone and pass quest, very fine CNC they process they have.

6. Install non-internally routed bars to make your life easier in the future .

Jokes apart, I think the procedure you describe is as correct as it can get. Probably if the fluid is relatively new (and particularly if it is mineral, since it is hydrophobic) there is no need to empty the circuit completely. If reusing oil, you can more or less stop it from coming out with a round toothpick

I have asked several sellers over AliExpress extensively about this. They don't seem interested. Pity because I think there is a market... They can produce them in carbon very cheap and there is basically no competition in western economies except for the pricey tailfin (which I am not going to buy among other things because I live in the Canary islands with special tax system and they refuse to remove the VAT, and not going to pay taxes twice...).

My ltwoo Rx worked basically ok, but I found a few annoying  bits  and ended up swapping it for a sensah teampro hrd 12s + GRX front and back.

- the screw on the back of the shifters that controls the engagement of the ratchet in the lever got a bit loose after a year and a half and started misbehaving while going up the casette. Could be corrected but a little annoyance.
- the rear derailleur has a buttery spring. They should have chosen a more robust one for sure.
- the same rear derailleur requires a change in pulleys to work well. Not optional, the stock ones were plain useless
- in the same rear derailleur... The b-screw is just cosmetic, it does nothing. Come one...
- the design of the brake calipers works, but it is absurdly weird, heavy and complex, and you end up having to adjust 4 screws (one of which very hard to access ... Annoying if it gets loose).

I'm not touching mechanical disc brakes again.
On the French ebay site, there are lots of people selling 105 shifters and hydraulic calipers for about 230 euro, which is probably going to be hard to beat.
I don't want to touch thumb shifters as they just feel prehistoric in my mind (right or wrong), and so that leaves the sensah team pro hrd but it must be very new because I'm struggling to even find it.

I got a quote on Alibaba for the Sensah team pro HRD shifters + calipers for 223 USD. Given that's before shipping, and with Shimano 105 shifters + calipers at around 230 eur in france, doesn't make sense to take on the brain damage of shipping + risk of beta testing unfinished products without customer support.

I have just installed the 12s teampros on my roadie/gravel, with grx 810 back and front . Still haven't found the time to give it a decent ride but the impression is very good. Very sharp breaking performance and crisp shifting.

I think they do. There is a YouTuber who got them done. But the weight savings are not dramatic and I think it will make the tubes more fragile (how much, we don't know).

I wouldn't do it for weight savings. If anything, do it for compliance.

I'm curious with the hydraulic hoses on fully internal frames. On semi-internal frames you can just detach the stem/bar from the bike and pack the bar sideways next to the frame in a box.

On fully internal frames, is this not an option for travel? Do you have to detach the hoses for travel? Sounds like a big hassle if that's the case.

I realized the same thing with my titanium gravel bike. Fully internal sucks big time. Never ever again !!!!!