I'm not an expert, but from what I've read the Loxone native implementation is focused on Device role only for now, so depending on your goal the 1home may still be necessary. In Matter, Devices are controlled by Controllers. So Loxone is focusing on letting Alexa, Siri et al control Loxone house. Whereas if 1home supports controller profile it will enable the Loxone ecosystem to control other Matter devices such as bulbs/shading/etc. Also, I'm pretty sure Loxone MS does not have Thread radio built in, whereas the 1Home server presumably does? (It's not clear on their website, that I could easily see). - FWIW iPhone 15 Pro has Thread radio built in so presumably this will become more common now in the usual cupertino-chasing way of things.
Home Assistant is currently focused on adding the Controller profile, so when I feel up to is I'll look at having Home Assistant controlling Loxone, as an alternative for the add-on Loxone integration. Using beta software against other beta software sounds like a recipe for hair-pulling, but at least Home Assistant is open source and a bit easier to debug through.
Whatever, Matter is going to be in beta testing for years, so anything you buy now is likely to be used for experimental and eval purposes for most of its lifetime anyway. (my reference point here is Bluetooth was in interop testing for over 10 years before it really started to get traction in the market, and even now 25 years after it was launched compatibility still sucks. And Matter is arguably solving a more complex problem, in a more complex way).
Another thing I found interesting in the Home Assistant notes is they recommend keeping using native (non-Matter) integrations where they exist indefinitely, as they're richer and support features that can't be controlled via Matter e.g. Hue lights.