it is unofficial repository maintained by me @hax4us. you can check available packages in README
mkdir -p $PREFIX/etc/apt/sources.list.d && printf "deb https://hax4us.github.io/termux-x/ x11-stable main" > $PREFIX/etc/apt/sources.list.d/hax4us_x11_stable.list
apt install x11-repo
wget https://hax4us.github.io/termux-x/hax4us.key && apt-key add hax4us.key
apt update
mkdir -p $PREFIX/etc/apt/sources.list.d && printf "deb https://hax4us.github.io/termux-x/ pentesting main" > $PREFIX/etc/apt/sources.list.d/hax4us_pentesting.list
apt update
apt install pkg_name
currently ruby (bigdecimal extension) is creating problems so after beef installation you will have to follow these step before executing beef
command
wget https://hax4us.github.io/files/fix-ruby-bigdecimal.sh
chmod +x fix-ruby-bigdecimal.sh && ./fix-ruby-bigdecimal.sh