ISO narrow-wide steel chainrings in higher tooth counts >30T I know Surly, Sram, RaceFace and Wolf Tooth have offerings in small BCD and proprietary fixing systems (cinch &amp; X-sync), but generally only come in one, MTB-range size.
Anyone know of a manufacturer with something more suitable to road/gravel drivetrains? i.e. 38+ teeth, 110/130BCD? Must be stainless steel!
Specific product recommendations are off topic here. However, we can point you in the right direction. At the time of writing SRAM makes 1x drivetrains for road, gravel or cyclocross bikes.

Perhaps start with SRAM Apex-1 or Rival-1.