Hello @irlcatgirl, swrast is mesa's slower software renderer, and the fact that Steam is trying to use it hints that you're using nVidia's proprietary driver, but don't have the driver's 32 bit userspace support installed. The nVidia proprietary driver requires that the running kernel module, 64 bit userspace, and 32 bit userspace are installed and have exactly the same version to work properly.
Please confirm that you're an nVidia user and find what nVidia driver series you're using with something like apt policy nvidia-driver-470 libnvidia-gl-470 libnvidia-gl-470:i386, then run sudo apt install libnvidia-gl-470:i386 (replacing 470 with the driver series you're using) to install the missing userspace support.
So I first uninstalled the default drivers and installed NVIDIA's .RUN file and it put my system into an unusable state. However once I removed it using it's uninstaller, I ran Ubuntu's driver autoinstall tool and now Steam works.
Nothing extracted yet.
Your system information
Please describe your issue in as much detail as possible:
Launching Steam fails, the updater briefly appears then it crashes