That just seems like bad luck -- if your phone is even somewhat popular, there's going to be a XDA forum dedicated to it. I used to have a LG L90, a low-end pho

That just seems like bad luck -- if your phone is even somewhat popular, there's going to be a XDA forum dedicated to it. I used to have a LG L90, a low-end phone bought for ~€120 that was by no means "flagship hardware". The phone shipped with Android 4.2, which was then OTA-updated to Android 5. Thanks to Cyanogenmod and later LineageOS, I managed to install Android 6, 7, and 8 as they came out, and only stopped using the phone after it physically broke down. Ulefone doesn't seem to be that popular -- it's not even listed among phone brands on the XDA forums (https://forum.xda-developers.com/all-forums-by-manufacturer https://forum.xda-developers.com/all-forums-by-manufacturer). If you want to have a €100 phone with LineageOS support, you definitely can (and do note that the LineageOS website lists only the "officially" supported models, not the community ports).