I'd sell off the etap 11 parts and move on to axs 12. I used a cheap shimano grx 46/30 with an axs 10-36 cassette to get a 30/36 or 0.83/1 ratio. The axs 36T capacity RD is the best choice, but it works with the 33T capacity model too. Both models have the same wrap capacity of 42-43T. The lowest mtb ratio would be a 42/52, if you wanted a similar low ratio and a decent top gear.

FWIW, a 1/1 ratio is the same, regardless of chain ring and sprocket combination used to produce it.