It is now possible to queue for Crossplay Multiplayer Quick Match : r/Rainbow6

Is Rainbow Six Siege Crossplay? ᐅ R6 Cross-Platform Details

Rainbow Six Siege's new season adds a new operator, map, and cross-play - Polygon

Cross-progression and crossplay are in the works for Rainbow Six Siege

Rainbow Six Siege Crossplay and Cross-Progression Launch Dates Revealed

Crossplay, cross-progression are coming in Rainbow Six Siege Operation Solar Raid - Dot Esports

Rainbow Six Extraction to feature crossplay between all platforms

Ubisoft begins testing Rainbow Six Siege crossplay, will outline cross-progression plans next month - Dot Esports

Crossplay between PC and PS5? : r/Rainbow6

Rainbow Six Siege cross-play and cross-progression still coming, but not to PC

How to Enable Cross Play - Tom Clancy's Rainbow Six Extraction Guide - IGN