This is a follow up question to Can I make a skeleton from a zombie?
In D&D 5e, there are very few ways to get a permanent necrotic follower. Usually you have to reassert control over them. Finger of death, I think, is the only way to get a permanent undead follower, but I am pretty sure that only applies to zombies, as cited below.
A humanoid killed by this spell rises at the start of your next turn as a zombie that is permanently under your command
I am interested in the exhaustion immunity of skeletons, and enjoy their appearance much more than the zombies.
Is it possible to get a permanent skeleton companion?