Termux doesn’t use systemctl or sudo, and there are many other commands that are not available. I modified the searxng.sh and lib.sh files because they were written for other operating systems like Ubuntu, Arch, Debian, and Fedora, but not specifically for Termux. So, I had to make some changes to make them work in Termux. I think I may have messed something up, though. I can send you the details of how I installed and configured it, or the files I modified, if that would be helpful.