Is there an alternative? If I want to build a flexible, high-quality, open whole-house audio system that my whole family can use without cursing my name, do I have any options?

It feels like there has to be a prosumer/low-end-professional product I can shoehorn into my house, kind of like how I've moved up from awful home network products to Ubiquiti gear over which I feel like I have some actual control (though their more recent UniFi products seem like a step backwards in that regard...)

But I'd still be afraid that it'd be fiddly and require too much maintenance. I really don't think there's anything commercial you can get that isn't kinda expensive, and almost certainly nothing that's open source / open hardware / open anything.