Hi @ptexas I believe what you are doing is right and Magisk is working. When you boot the Magisk patched boot image, you'll be booted to the Android system only. Magisk is a root utility for Android, which means you get root/superuser access when you have Magisk installed/loaded. So, if you want root access within your Android, you can follow the remaining instructions in the guide to complete the full installation.
If you are looking to install a ROM, then you do not need root/Magisk. What you need is TWRP (or fastboot directly if the ROM is an img file that you can flash via fastboot). So, something like:Flash TWRP (fastboot flash boot twrp.img) to your boot partition (since there is no recovery partition in Android anymore) Reboot to TWRP Flash the ROM within TWRP Change the active boot slot Erase userdata (factory reset) Reboot
Adding to that, please do follow any device-specific instructions. For example for the Nokia 7.2, you will also need to flash vbmeta with disabling flags included. Please follow the XDA threads about the steps to install.
Let me know how that goes :)