The RBY Room has a new feature for those looking to find matches on PS. You'll see a new button where the marquee text scrolls past.
When you click it, you'll get a nice little interface to add new roles with. Click the button to get roles for various RBY metagames, and type them in as seen there to ping people for them. This is much like what the RBY Community Discord uses for its matchmaking channel, just now on PS for something far more accessible.
Given the large array of RBY formats that PS offers, this makes up for the lack of a ladder for non-OU metagames, no? Give em a try!