When you say "just... run linux", are you referring to termux, or something else ? How do you run a linux userspace in Android ?
https://www.linuxjournal.com/content/bringing-desktop-linux-...
https://source.android.com/docs/whatsnew/android-16-release#...
While this is mostly a KVM setup, there's nothing specific about Android that prevents a linux userspace from running in there. Each app is almost one already. Most of its core components have been integrated into linux's main repository (like binder), and AOSP isn't that far off from a regular Linux. Sure, zygote, user & power management are not exactly a standard install, but they're not that crazy either
What sort of tradeoffs would I see? Performance? Battery life? Security (secure enclave access?)