currently i build a pkg called
kernel-alive ( name not definitive ) in unstable just now for testing
This pkg backup the current kernel in use ( pre transaction hook ) and after transaction ( post transaction ) move it in /lib/modules directory . In theory in this way the modules of current kernel continue to work after kernel upgrade . When pc reboot a systemd service clean the modules of the previous kernel so you use the actual kernel ..
I have tested in my hands and all work but i can't verify if work in any condition . Test it and i 'm open for any improvment or correction