now Iโ€™m sad that they donโ€™t exist:(

If I had the funds I would start a octopus farm and use artificial selection to make them land dwellers. by gradually encouraging them to get food from the forest.

anyone willing to fund me?

with enough funds Iโ€™ll also domesticate them so they can be nice household pets. no, we will never let the Deep to adopt one or step on our premises.

You just have to wait 10k years

based on Russian fox domestication experiment, 50 years of artificial selection can turn a wild fox into a household puppy. although Iโ€™ll admit, itโ€™s likely way easier on social mammals as all they did is mess up their neoteny (extend child like traits into adulthood), in no stage of an octopus life they are sociable, so it might be harder.

slightly related trivia, most animal domestication involved neoteny, and it also happened to humans, so it is correct to say, we humans also domesticated ourselves.