I am still searching for reasonably priced T-Shirts that only have seams from the armpits to the hips (one such seam per side), and optionally at the 4 holes for edge reinforcement. Critically, this means no seams on top of shoulders by any reasonable definition of what "on top of shoulder" means.

You could knit it on a tube knitting machine capable of adjusting loop count/circumference freely.

But for a T-Shirt you have very fine knitting, so regular knitting machines can at best do newborn-sized T-Shirts.

If anyone happens to know where I could order a dozen shirts knitted to spec based on knit design rules and published-by-them loop-pitch-after-first-wash from cotton, I'd love to hear.