Well. It doesn't say in any docs or specs, but for what it's worth, Valve's hardware has always been open like that. You're free to install windows on your steam deck, for example.

> Well. It doesn't say in any docs or specs, but for what it's worth

They do hint that you can install a different OS on it:

> Just like any SteamOS device, install your own apps, open a browser, do what you want: It's your PC.

Every other SteamOS device does allow you to install whatever OS on the device, so seems Frame will be the same, judging by that landing page blurb.