Will hopefully help the handheld performance/battery. I know I personally have been waiting for FSR 2 before really getting into BG3 on my deck.
As an odd side note, FSR 2’s addition to the game wasn’t mentioned in the patch notes. Also there’s a negative interaction between TAA and FSR 2, so you’ll have to set anti-aliasing to SMAA or disabled if you want to use FSR 2.
Both FSR 2 and the anti-aliasing setting are in the BG3 settings menu.