Honestly, I didn't even know that one could do a graphical environment on Termux (as XFCE and GIMP would entail) with it. The Termux I know on Android is an app in F-Droid that provides a terminal-only environment. So I don't really know what-all is packaged for the environment you're using. Just saying that traditional Linux distros will have those.
EDIT: You might run a pkg update in Termux to update the index of currently-available packages, then try installing it.