In the end I bootstrap directly into stage3 and using chroot.
For doing this is pretty straightforward and probably just busybox command is enough.
Make gentoo directory.
mkdir gentoo
Download stage3 i686 files.
wget http://distfiles.gentoo.org/releases/x86/autobuilds/current-stage3-i686/stage3-i686-20161227.tar.bz2
Untar the file.
tar -vjxf *.tar.bz2 -C gentoo
Get in the chroot.
maybe ln -s /proc/self/fd /dev is needed.
export GENTOO_ROOT="/data/data/com.termux/files/home/gentoo/" cp -L /etc/resolv.conf $GENTOO_ROOT/etc/ mount -t proc proc $GENTOO_ROOT/proc mount --rbind /sys $GENTOO_ROOT/sys mount --rbind /dev $GENTOO_ROOT/dev
unset LD_PRELOAD
in make.conf i’m using
FEATURES="-userfetch -sandbox -usersandbox"
next will be trying to install plasma mobile on Gentoo