Quick answer: Path of Exile 2 leaves Early Access with its 1.0 release on December 11 and goes free to play the same day. The update adds Acts 5 and 6, two new classes and a passive skill tree rework.

Path of Exile 2 is leaving Early Access. Grinding Gear Games' action RPG hits its 1.0 release on December 11, and it goes free to play the same day. The release adds the final parts of the story, so you can do a full playthrough.
Acts 5 and 6 bring 24 new areas and 18 new unique bosses, plus more than 20 new Champion Rare encounters with their own mechanics. There are also new items, tweaks to existing classes and a rework of the passive skill tree.

Two new classes are coming too. The Shadow uses a new Stealth mechanic, where monsters can't see you until you get close, and being in stealth powers up dagger skills. It also brings Traps as a new weapon type, and its Ascendancy classes at launch are the Assassin and the Infiltrator. The Duelist uses Stances: Ready Stance boosts sword skills and can be upgraded to Sand or Blood Stances. Its Ascendancy classes are the Knight and the Master-at-Arms.
GamingOnLinux says the game has run well on Linux through Proton for a long time, and Valve currently rates Path of Exile 2 as Verified on Steam Deck.