Thankfully there's livepatching (e.g. https://ubuntu.com/security/livepatch )
6.19 added a new Live Update Orchestrator, which allows significantly more of the system to be retained while doing a kexec / Kernel Handover like transisiton to a new kernel too. https://www.phoronix.com/news/Linux-6.19-Live-Update-LUO https://lwn.net/Articles/1033364/
Systemd added support in recent 2.61. Theres also now ways to have user stores, that survive across switches. https://www.phoronix.com/news/systemd-261
alt Hacker News
6.19 added a new Live Update Orchestrator, which allows significantly more of the system to be retained while doing a kexec / Kernel Handover like transisiton to a new kernel too. https://www.phoronix.com/news/Linux-6.19-Live-Update-LUO https://lwn.net/Articles/1033364/
Systemd added support in recent 2.61. Theres also now ways to have user stores, that survive across switches. https://www.phoronix.com/news/systemd-261