Ok,
Let’s try
.
on the phone, in developper options, you need to enable USB debugging and root debugging
now boot the device into TWRP
.
in the terminal on your PC, run :
adb shell
.
dd if=/dev/block/sde49 of=/sdcard/boot.img
you should find the boot.img at the root of your device internal storage
or
dd if=/dev/block/sde49 of=/external_sd/boot.img
you should find the boot.img at the root of your physical SDcard
.
Edit :
i have just tested the commands using one of my (old) test devices,
it worked !
the dd command have successfully generated a file called boot.img, and despite it is bigger (10.5 Mo) than the original one from the samsung firmware (7.8 Mo) and from /e/ build .zip i run on the device (5.1 Mo),
using TWRP, i have successfully reflashed the newly generated boot.img on the device witch can reboot and run as usual.
so you can try to pach it using magisk to see if magisk accept the job.