I have a little experience with the well-kept secret Ubuntu mini.iso. This installs via network and has many “minimal” options including MATE desktop.
Long story short, minimal seems to be only the ubuntu-mate-core package. The ubuntu-mate-desktop package adds the heavier stuff.
All the Ubuntu desktops and server are available on this 58M ISO but you need a hardwired network. What’s nice is you start up to date on everything.
HTH