Depending on how big the insurance company is and how representative their members are, that would seem to be a pretty decent proxy. Should be pretty easy to figure out how many of the excess deaths are at least officially attributed to covid. Not as easy to figure out if the other excess deaths were possibly caused by covid complications or otherwise attributable to Covid but not officially recorded as covid, which might have been due to lifestyle changes due to government reactions to Covid (e.g., excess suicides?), which were due to more or less unrelated issues (increased crime after police reducing proactiveness due to increasing anti-police sentiment), or which may have been contributed to by the vaccine.