I can only speak for myself, but my honest answer would be that indeed, self-hosting probably won't be easy to do any time soon. We're trying to get a less technical audience to benefit from privacy protections too, and I don't think there's a good approach to get them to self-host as well, so focusing our limited time on other things is probably more effective. But who knows, actual use and user research do influence our roadmap, so nothing's set in stone.

But you're absolutely right, the caveat is indeed that the reason you care about open source does matter. If you want to self-host, you're probably better off with another product. If you want to be able to see what code is running, or even be in control of the running code yourself (even if it's running on someone else's servers), then Relay might be interesting too.