Not sure how i can add a 0.5mm C shaped spacer to the headset. Can't it just slip out or the compression will hold it in place?
I think i will go ahead and order the Specialized design mentioned by @fabxyz on ali

Compression would keep it in place, shouldn't move. And you have hoses in the part that requires it to be C shaped rather than a full ring anyway, so it can't really go anywhere.

That said, if there's a cheap AliExpress version that is known to fix the problem, it's probably worth biting the bullet, if you tell me I can pay 20 bucks to get rid of play for good, I'd make that trade every time.

Very nice, except the t700 800 mix, and to a lesser extent, weight.
How much do they sell their frames for usually?
This frame in a lighter / stiffer version with t800/1000 could be pretty amazing.

Thank you.

Thanks for the reply.
I actually tried a different brake with the same results. Ie unable to bleed so yes I believe something is wrong with the shift lever itself.

New frame just popped up on Speeder Cycling's site today. Looks good, but we only get to see a render for now.

https://www.speedercycling.com/Carbon-Integrated-Road-Disc-Frameset-SC-R55D-_p429.html
Material: Toray M40J T700 / T800
Type: 700C Road Disc
Appearance: UDM
Finish: Gloss / Matt (can offer custom painting)
Headset: FSA NO.55R ACR 1.5" Fully-Integrated
BB: Press Fit BB86.5*41mm
Standard Weight: 980g+/-35g (51cm)
SL Weight: 880g+/-35g (51cm)
Frame Size: 45cm / 48cm / 51cm / 54cm / 57cm
Handlebar Size: 370mm / 390mm / 410mm / 430mm (C to C in hoods)
Stem Size: 85mm / 95mm / 105mm / 115mm / 125mm
Cable Routing: Full Internal
Di2 Compatible: Yes
Disc Mount: Flat Mount
Max Tire Clearance: 700 x 32c
TA: 12x100mm / 12x142mm
Test: ISO 4210
Warranty: Two Years