The thing I would really like to know is how to run orca from a source tree confidently knowing it’s not reaching into my distro’s version (MATE 20.10, orca 3.38.0). I’ve not tried to compile it yet but I’m hoping getting the dev libraries from the distro’s orca will suffice.
You can set --prefix=directory-name when you run ./configure. Then, "make install" will install Orca into the directory you specify (e.g., somewhere under $HOME).
At that point you can run bin/orca from wihtin that directory. From memory, when I last did this, I ran it with orca --replace to replace the currently running instance.