I’d really like to be able to root/install lineage OS on my Motorola g73, but it seems it needs custom software written for it to have a custom ROM, or even TWRP, which I need to install Magisk. I could also patch the boot image, but that isn’t distributed by reputable sources for my phone, and my phone would already need to be rooted to extract it via ADB.
Before getting the phone, I didn’t know devices had to be on a specified list to be able to be rooted.
Yeah, it’s best to confirm that someone somewhere has rooted a phone before you buy it for that purpose. Motorola typically allows it but there may be exceptions.
I was able to unlock the bootloader, but I couldn’t install Magisk or TWRP for it.
Would Shizuku be an option for you? That’s privilege elevation similar to root but you don’t need to unlock the bootloader for it. Pro is definitely that banking apps and OTA will still work afterwards. Cons are it’s a bit finicky and apps written for root still won’t work if they don’t explicitly work with Shizuku, too (some of them do). You’ll also be able to uninstall apps for user 0 which aren’t uninstallable otherwise (like gboard on G72, when I had one).
If you can’t find anything on xda-developers.com/ or its forum then it’s probably not possible at the moment.