Brownells now has G17 Gen4 RMR Slides for sale, as well as G43 slides
G43 slide
https://www.brownells.com/handgun-parts/slide-parts/slides/slide-for-glock-g43-prod123564.aspx
G17 Gen4 slide
https://www.brownells.com/handgun-parts/slide-parts/slides/rmr-cut-slide-for-gen-4-glock-9mm-prod121024.aspx
From: Brownells