I've had a quick word with Mike over at wolftoothcomponents.com about a possible 1x chainring for the 120BCD of the existing Quarq/SRAM S2275 MTB power meter. He'd be keen to know if there is a market for these rings.
If you're interested, send me a PM.
It's tight, but you should be able to get a 36 and up on the 120BCD, then just ditch the inner. The chainring design should allow a slight offset for correct line. I think the goal of an initial production run would be a 36 tooth for MTB, and something around 44-46 for a cyclocross 1x setup.
The current tooth profile for his rings looks like the original expired patent: