

It would require an entire separate TPM chip, integration of it on the main PCB, and all the the firmware and software handling that comes with that, and collaboration with the GrapheneOS team (which I hear on forums and people who have worked with them, is often not a pleasant experience) for an extremely small percentage of their sales.
Doing /e/ or calyx would definitely be significantly easier.
Some drives are worse than others and higher capacities get worse and worse, in my experience, Seagate drives are extremely loud.
If you get helium drives (like wd red plus > 8TB i think),or 2nd hand hgst/ WD enterprise drives) they are significantly quieter.
But, having an ssd is cheaper probably. I have an SSD for the boot drive and all databases, configuration folders, etc… In docker so general IO is fast, then media, documents, pictures, etc… On the big HDDs.