That would be very cool but, sadly, 60% of that market is in this comments thread. And we want it to be open source.
It's really a supply side issue pretending to be a demand one. Self hosted services of all kinds are woefully underdeveloped.
Tech giants aren't going to encourage you to own your data and hardware by spending effort on supporting it, because that undermines key reasons for building cloud services: surveillance and control.
On the contrary, it would make a lot of sense for Amazon to work on open source self-hosted server apps, because they would seem to be the answer to the question, "Why would a non-techy want a cloud VM." Surely their PMs must day-dream about a future in which a cloud VM is as common a monthly fee for a middle-class family as a gym membership or netflix subscription, right?
Many, many HN users want open source primarily for ideological reasons. A closed-source solution (or even a source-available one) is unacceptable for that reason alone, and not related to cost or practicality.
If the server software were confined to macs, that would also act as marketing just like iTunes was mac only for a while. Though I recognize Tim Cook seems far more interested in selling additional services than hardware unfortunately.
Unfortunately, iCloud works well for probably 99% of their user and, like someone in this thread said, the only people interested in this service are in this thread.
Users who aren't tech savvy who are trying to run their own mission-critical software on their own hardware:
1. Should expect to pay $200+/month for a support plan. That will buy them one hour of an engineer's time per month. They are going to need that time, because deploying software is hard, keeping software running is hard, and there are no SRE/DevOps economies of scale when every Tom, Dick, and Harry wants to run their own service on their own hardware.
2. Should expect to either deal with all the problems (stability and security) that come with regular auto-updates, or regularly getting pwned (because they aren't auto-updating, and because they are a juicy, high ROI target for bad actors).
3. All this stuff already exists for enterprises, and they aren't complaining in these HN threads, because their needs are being met by cloud providers (As are the needs of politicians. Because they generally don't need security, they need security theatre. As long as they can check the compliance checkbox, they are in the clear.) The people whose needs aren't met are the long-tail small-fry of journalists and hobbyists and their ilk. Who aren't enough of a market, and can't afford the money, and the time, because see points #1 and #2. Like, maybe the NYT can afford to have this set up, and set up well for their people, but they already have dedicated IT teams doing just that!
I don't see how that bit would be a problem. The market size, yes, it's a problem, but it's supposed to be a cloud service, there is no loss on the clients being open source.
I think Synology is the closest product I know of that provides something like what you're describing, though, as you point out, it's not OSI open source.
I don't see a solution for this. Billions of people and probably a ton of people reading this on hacker news like me have their stuff at google or another top cloud provider. Google causes untold suffering for people by not let people recover their accounts. There was the recent librarian letter requesting help for people this happens too. We might know someone at google to ask for help. Wonder if this person did.
Most importantly, due to users hosting all the data using their own physical space, electricity, and bandwidth, the incentive for Synology to scan everything stored evaporates: they are not on the hook for illegal files hosted on a server in someone's home. I think the picture is less clear when it's Google or Apple doing the hosting, which leads them to scan people's files as a policy.