I tried 'apt-get install' by mistake. I see your help file uses 'apt install'. I tried 'apt install picolisp', but no luck. Do you have your own package repository? Thanks.
Yes, the repository is an app-specific one, containing cross compiled (and sometimes patched) packages to run directly without chroot. Just tell me about desired packages (such as picolisp) and I will look into adding them!