gopip is a container that builds python3 packages and return a zip archive for you. It is able to build more than one package in the same request and a form can help with packages from git repositories. This web service is currently available at gopip.
The interface features light/dark mode based on your system's preferences, also, I designed it to be minimalist, the page is basically a form. The back-end is currently running on Google cloud run and costs nothing for me, it consists of a container and a pip install command.
This is the repo with the source code.