I have a lot of old phones that I never got rid of. Is there a definitive list of devices capable of being rooted? From what I understand, the bootloader is locked on all of them. How do I figure out how to root in the first place? The internet plagues me with scamware search results (useless "root tools"). Direct answers are welcome
Honestly just google it, it depends on the device. If the bootloader is not unlockable, you're screwed, basically. And then, assuming the bootloader CAN be unlocked, you're hoping that some devs actually took the time to make alternative ROMs for the phone. Check XDA for that.
Usually if you have the boot.img file for your current instance of Android you can root most devices using magisk. Make sure to turn off auto update though
I've never had a device I wasn't able to root, though more recently I haven't found the need to root. Latest phone being a Pixel 7 Pro running GrapheneOS. Check XDA forums for rooting info on phones old and new.