If using systemd-oomd, you can launch Firefox into it's own cgroup / systemd.scope, that has memory pressure control settings set to not kill it. ManagedOOMPreference=avoid.

https://www.freedesktop.org/software/systemd/man/latest/syst...

There's a variety of oom daemons. bustd is very lightweight & new. earlyoom has been around a long time, and has an --avoid flag. https://github.com/rfjakob/earlyoom?tab=readme-ov-file#prefe...

Your concerns are very addressable.

Yeah sytemd-oomd seems tuned for server workloads, I couldn't get it to stop killing my session instead of whichever app had eaten the memory.

Honestly on the desktop I'd rather a popup that allowed me to select which app to kill. But the kernel doesn't seem to even be able to prioritize the display server memory.