Honestly, you are quite a more advanced user than I. I had issues with the reboots as well until I flashed the patch and then immediately the /e/os zip. I did not reboot prior to flashing /e/. After this, I no longer had reboot or sim card recognition issues.
I do not know the exact workings of the patch. Another user on /e/'s gitlab described the patch as having fixed their reboot and sim card issues as well.
Dan.