This might sound creepy, Noah, but I proposed almost exactly the same idea in 2016 to my business partners! I pitched it as a “digital time vault” inspired by the Time Vault in Asimov’s Foundation series. At specific moments, eg when a grandchild graduates from college, turns 21, or gets married, they get a link to a prerecorded message from a long-passed grandparent to remind them of their loved one. The problem with this idea is that it requires so much customised work in script writing, filming, and archiving the data for the long-term that we could not make the economics work. Like you said, it was a tough sell and I didn’t think many people would be willing to spend so much time on contemplating their eventual demise.
The next post-mortem services idea we had was augmented reality gravestones with timed features so prerecorded messages would play if the visitors scanned the QR code on specific days and enter their password. I saw it as a way to make sure the damned kids and grandkids visit. Never went ahead with the idea though.