The reason P3 is being used in computer monitors is b/c it’s the next, little incrementation of color gamut. So it gets dished out, like crumbs, until the market is saturated. And then the next increment comes. How convenient... Also, it’s quite old.
P3 is basically a trim pass, these days, used for film outs (for the 5 theaters left who still project film), just like 709 is used for HDTV. Every colorist should be doing final color in XYZ. And even then, there’s now an argument for mastering in HDR and even making SDR an addition trim pass.
For gamers, all you need to know is that P3 is to 709 what AdobeRGB is to sRGB. More colors. More pop. BUT, in the real world, 99.9% of colors don’t extent into those neon red and greens. Sure, it’s fun to look at. But it’s not going to impact your actual gaming. HDR is kinda the same. It’s cool and fun to look at. But technically it’s going to be harder for your eyes to adjust >quickly< to the additional contrast. So for RPG and strategy, eh, sure. But for FPS, stay away. Stick with da’ hertz