You just have to somehow speedrun the decades of development that went into Android to make it decently run on mobile hardware.. never really understood this "throwing out the baby" direction - the UNIX userspace model simply doesn't work on mobile (I would wager it also doesn't work on desktop anymore), has no security (everything runs as your user which made sense when you ran some batch job on a terminal with multiple other users, but nowadays when a single user has as many processes as all the user had back then it effectively means no security between any of those programs), there is no real resource control, no lifecycles, so the device will burn scorching hot and have terrible battery life.
On Android (and iOS) apps were always living in a world with lifecycles so if they wanted to operate correctly, they had to become decent citizens (save state when asked, so they can be stopped and resumed at any moment). This also fits nicely with sandboxes and user permissions, etc.
So without developing an alternative user-space for "GNU-Linux", it's simply not competing with android in any form or shape.
And even if you do, now every GNU app has to somehow be ported to that userspace API (you can't just kill GIMP or whatever Linux process)