Live Kernel Patching has been around for about 20 years[-1] now.
Red Hat Enterprise Linux[1] and Oracle (Enterprise Linux) Unbreakable Linux[2] both use it as a selling point.
This feature is still a bit ad hoc because, in most setups, rebooting a system isn't a huge burden and is much simpler than using boutique commands to live-patch it.
Live patching exists but it tends to cap out at around a year of updates for any particular kernel version. It's not getting you anywhere near 1000 days.