No, termux isn't a container, it's running directly in userspace on the host. The only weird thing is that because it's running directly on the host, it has to be built to use unusual paths, eg. /data/data/com.termux/files/usr/bin/bash instead of /usr/bin/bash. If it used containers (which IIRC it can't because Android doesn't really support it) that would actually be easier because then it could use a chroot to make the paths look normal.