OS will not mount the VM partition. Virtual memory must be forced to work
Solution 1:
Solved. Cobbled together a workaround with information from interwebs.
Created this plist named “local.mountdisk1s4.plist” containing:
Label
local.mountdisk1s4.plist
ProgramArguments
/sbin/mount_apfs
disk1s4
/private/var/vm
KeepAlive
SuccessfulExit
Placed it in /Library/launchdaemons
Swapping now works as it should. Still not sure how this all broke in the first place, or if there's a more elegant solution.