Nintendo’s mobile initiative and Sony’s multi platform ones are different. Nintendo wouldn’t let Samus be in Fortnite because Epic wanted her playable on other platforms. Sony is actually developing a full game with Aloy in it and purposely putting it on the Switch.Mario Kart Tour on Mobile didn't mean Nintendo is bringing over mainline Mario Kart games to mobile and it never did. It was clearly a spin off game that was more closely related to the main games even though here Lego Horizon is a completely different game thematically and scope wise as well as it's branding is important because it's using LEGO to market it.
If anything, the downplaying is coming from Sony/Playstation haters trying to downplay the LEGO brand and making it seem as if Horizon is bigger than Lego which I KNOW none of you guys would ever say seriously but have arguments in bad faith and pretend y'all not trolling though.
Once you compromise your principles especially for money it get easier and easier to do it for more money. They might not be doing it now because they think it doesn’t make financial sense but if they think it would work they’d do it.
Nintendo even if they thought it would make financial sense would refuse as they did with Samus.