Well basicly all instruction you need and it’s explained pretty well on the lineage os website itself. https://wiki.lineageos.org/devices/m8/ The hardest part was getting the unlocktoken since htc doesn’t take new htcdev registrations. I got hellped by a member on Lemmy who had a old htc dev account.
The short awnser is: https://wiki.lineageos.org/devices/ The m8 also wasn’t supported anymore but since mine will mostly/only be used for media playback (you know, great speakers) so security isn’t my bigest concern.