alt Hacker NewsThis. Also, for phones that don't support Android virtualization, there's a user-space hack, part of Termux upstream, that allows for root-less chroots via LD_PRELOAD: https://wiki.termux.com/wiki/PRoot.
systemd won't boot with this (needs to be PID 1), but a lot of software will work just fine and there's nearly zero emulation overhead.
I don't think it uses LD_PRELOAD, it uses ptrace to intercept system calls (hence the name). Unfortunately this does have performance overhead, although I've never bothered to measure it. Actually that would be an interesting thing to benchmark.