They asked chatgpt and it told them that it is more stable.

Orange Pi has been working with Manjaro on a steam deck clone (with touchpads). Make Zotac bought/licenced their design?

I would bet that for Zotac, they still want a support/integration contract and maybe Manjaro have setup to actually have a business plan now. SteamOS, maybe going to Valve for support is more expensive or they're not staffed well enough to onboard Lenovo, maybe Asus and any of the actual big PC vendors

Yeah, with Arch the install and initial setup is the hard part, but they do that for you so I don't get the point of going with Manjaro.