I think the biological route is also the more ideal one when we go into immortality/extra long life kind of territory. The makeup of biological life is just far more adaptable and robust, self-sustainable, and just more efficient in general.

The main reason mechanical means are appealing is the same reason why it's sometimes challenging to work through manipulating biology: It's easier to engineer a machine to follow programmable code than it is to get cells to do what you want them to do. It's also a lot more difficult to reverse engineer something so complex that wasn't exactly designed so much as built up through eons of adaptation and mutation.

If and when we manage to unlock those many missing pages in the blueprint/manual though, there's a lot of possibilities we might have available. And not all of them are stereotypical science fiction nightmares.