Pathfinder playtests give you the opportunity to participate in finalizing rules and new materials, including new classes, spells, ancestries, feats, and more!
Beat me to it while I was summarizing things. Reproduced below:
Commander
The commander is an Intelligence-based tactician with unparalleled authority over the battlefield! But they’re no slouch in the fight themself, being trained in martial weapons and all armors, so if you want to lead your fellow adventurers to victory, be sure to playtest the commander!
The Commander is a support martial class that buffs the party using Tactics to grant 2+INT party members extra reactions. They also buff nearby allies with a fear-opposing aura.
Guardian
The guardian is a Strength-based protector who excels in the use of armor, both for their own benefit and the aid of others. If you are the type of player who enjoys keeping others safe from harm, be sure to playtest the guardian!
The Guardian is a pure martial Tank, with some features that seem to be similar to Champions without the magical element. A defensive expert, focused on redirecting damage away from allies and towards themself, they have abilities that buff ally AC, and nerf enemy attack bonuses against allies while buffing those bonuses against themself, incentivizing enemies to attack them first.
Both of these look extremely interesting to me, at least on first pass. I currently have a Champion DMPC in my home game with my step-son that I could and might just re-build as a Guardian. I never wanted the magical elements anyway, and have largely been ignoring them (besides the very useful Lay on Hands spell). I'd be losing that self-healing, but I haven't been able to make the most out of my reactions because the fam keeps staying way back while I try to intercept.
This would allow me to be more active in forcing enemies to attack me without just meta-gaming it, while still giving me reactions that are similar to what I (don't) use as a Champion.
User u/Acceptable-Worth-462 over on Reddit put together a custom Pathbuilder JSON package for the Guardian. I've tested it on the Android app, and it's working. I've also coverted my Liberation Champion!
Edit: They tweaked and re-uploaded the JSON. Apparently they had a bug in the file relates to Weapon Specialization. (Old file has been moved to the bottom of the post)
u/Acceptable-Worth-462 came back with a Commander module for Pathbuilder. Unfortunately, Commander's chassis doesn't quite fit the existing mold, so Pathbuilder support is... a little wonky. I'll let the OP explain:
Regarding the Commander: currently the possibilities given by the Pathbuilder 2e app are somewhat limited, which made the implementation of the Commander Tactics rather tricky. Basically, give yourself 4 free feats at lvl 1, that you'll use for the lvl 2 Tactical Expansions (NameOfTactic) feats.
Do it again at lvl 7, lvl 15 and lvl 19 for the Expert, Master and Legendary Tactics respectively. Anytime you actually pick the Tactical Expansion feat, just give yourself an extra class feat which you'll use for another Tactical Expansion. I realize this is not ideal, but that's the best I managed with the current state of Custom Packs in Pathbuilder 2e. If anybody knows of a better way, I'd be thankful