ERROR: Could not build wheels for PyNaCl which use PEP 517 and cannot be installed directly

PEP 517 was known to have some problems with virtualenvs so that could be a likely cause.

Try to perform these commands and see if that works

pip install --upgrade pip
pip install --no-use-pep517 discord.py[voice]

If not try to downgrade your pip version

pip install pip==18.1

and then try the package install command again.

Thanks, @kyrisu, your solution actually worked installing make did the trick for certain cloud packages it throws an error if there is no cmake installed too. Adding the command which I used on my alpine image.

RUN apk add --no-cache make cmake

This adds both make and cmake and post that the dependencies are installed without any issues.

Try to install binutils first before installing pynacl on Termux.

pkg install binutils

[root@username ~]# pip3 install -U discord.py[voice]

above worked for me ^^ on RHEL 8.