Guns of Alkenstar Bundle is a surprisingly small bundle for $30 (previous Pathfinder bundles have had more for less money). You do get core rules and supplements to run Pathfinder 2E. You get a half-sized adventure path (taking your PCs to about level 10) of three adventures centered on a Steam-tech city that has guns. You get some setting material for Lost Omens, which details the main setting world of Golarion.

Overall don't think it's worth buying.

Pathfinder 2E Beginner Box
Pathfinder 2E Core Rulebook
Pathfinder 2E Bestiary
Pathfinder 2E Advanced Player's Guide
Pathfinder 2E GameMastery Guide

Lost Omens: World Guide
Lost Omens: Character Guide
Lost Omens: Impossible Lands

Pathfinder Guns & Gear

Outlaws of Alkenstar Player's Guide
Punks in a Powder Keg (Outlaws of Alkenstar 1) + Foundry VTT Module
Crade of Quartz (Outlaws of Alkenstar 2) + Foundry VTT Module
The Smoking Gun (Outlaws of Alkenstar 2) + Foundry VTT Module

Pathfinder One-Shot: Head Shot the Rot