I figured it out. The iGPU on newest Gen AMD was causing almost everything.
I can’t upload a screenshot, but in the sudo dmesg | grep BAR command, I noticed something I didn’t notice the first time around: VRAM RAM=512M
I’m blaming Gigabyte for this. Apparently “Auto” on the integrated graphics setting means “I’m on even if you have a dGPU”. Setting it to disabled has fixed my ability to launch games, and (almost more importantly) has all but resolved my freezing issues. The freezing is down to like, 2-3 seconds, and only once or twice when a game launches. Tolerable.
I speculate that there is some kernel, driver, or some other logic in place that is assuming my Intel GPU is an iGPU and my AMD GPU is a dGPU, which would be a valid assumption given that only in this exact generation (discounting APUs which I think appear differently) is it even possible for it to be the other way around.
Anyways, thank you for all the help folks! It was specifically that ReBar command that got me thinking about it.