I ignored it and continued to install pyinstaller. It also ended with successful message. When I tested it, the same "not include a pre-compiled bootloader" error showed.
Here is what I get from /proc/cpuinfo. It's NanoPi Neo with 4 cores.You’re on arm7l which pip and PyPI don’t support so that’s why PyInstaller can’t ship precompiled bootloaders for you. Most Pi users can install packages from pywheels
which contains a specially compiled copy of most common packages (see their home page for setting it up) but first, what is the output of ldd --version
on your Pi? If it says glibc then go ahead and use piwheels. If it’s musl then this is going to be harder…