does this run android? or some other ui? Is that UI and underlying system tailored for mobile like android is? I feel like android probably has a ton of work put in to take constraints of phone into consideration
This is a "normal 'GNU/Linux' distro" (well if NixOS is normal for you).
Just like NixOS doesn't prescribe a user interface, it is left to the end-user to choose what they want to run.
As such, this is meant to allow you to run the "mobile first" desktop environments like Phosh and Plasma Mobile. As many other non-Android Mobile Linux distributions do.
So to answer more succintly: no, it doesn't run Android. Yes, some other UI, at the end-user's choice.
Just like NixOS doesn't prescribe a user interface, it is left to the end-user to choose what they want to run.
As such, this is meant to allow you to run the "mobile first" desktop environments like Phosh and Plasma Mobile. As many other non-Android Mobile Linux distributions do.
So to answer more succintly: no, it doesn't run Android. Yes, some other UI, at the end-user's choice.