You: "Partial reprogramming is supposed to reverse multiple aspects of aging [..] it’s been labelled by many as age reversal, not just targeting a single aging subpathology."
I agree w/ you that it has & I disagree w/ the people marketing it that way (eg PR on Life Bio's ph1 starting). All aging subpathologies (hallmarks or whatever you want to call them) interact with & affect most if not all of the others, and (partial) epigenetic reprogramming may be the one with the biggest influence over others but that doesn't mean it fully fixes (or even reverses) any or all of the others. The PR around Life's ph1 is overhype. Maybe that inaccurate overhype is good for the field by exciting outsiders---hard to tell.
You: "And if we’re not extending longevity then what’s the difference between longevity science/biotech and other forms of healthcare?"
The geroscience hypothesis. Disease-specific medicine finds targets in disease-specific causal chains & interferes with them. Aging science finds targets upstream of those, in other words causal chains upstream of the age-related chonic-disease-specific causal chains that are specifically upstream of multiple chonic diseases and aging biotech interferes with those. The key consequent difference then being that those interventions can then likely mitigate multiple diverse age-related chronic diseases, unlike traditional medical interventions.
But since there are multiple diverse shared pathological causal chains (which we call SENS areas or Hallmarks or the term I prefer for its genericness at encompassing both of these paradigms: aging subpathologies) each of which can be life limiting, only by meaningfully mitigating all of them can one dramatically increase lifespan. So until combination therapies of several therapy types are in the mix it's best to measure progress by tracking simultaneous mitigation of multiple age-related diseases & aging-subpathology specific ways to measure progress in that area together with a checklist of areas listing the progress against each.