I messed something up.
I was eventually able to get a Windows machine to recognize it when I did fastboot devices, so I did try sending my Magisk file over via fastboot flash boot and I got the following message:
C:\Users\xxx\Desktop\platform-tools>fastboot flash boot magisk_patched-24200_esClI.img
Warning: skip copying boot image avb footer (boot partition size: 0, boot image size: 17901568).
Sending 'boot' (17482 KB) OKAY [ 1.018s]
Writing 'boot' OKAY [ 0.379s]
Finished. Total time: 1.464s
And now my 4e is stuck and won't seem to reboot or anything. I can still see it under adb devices and fastboot devices, so I tried to flash the boot.img file over to it and got the same message as above, but I still can't get anything to change on the screen.
Any ideas would be really appreciated!